The man
A few thoughts tentatively offered, not as authoritative by any means, although based on past reading and research.
However you build an alternative history of Wallace's career, I think you have to begin with Wallace's personality. I don't think it's historically accurate to say he had no central core compelling beliefs -- Communism, for instance, would never have been on his platform -- but his core derived from an inner psychological turbulence that limited his ranges of choices within a narrow frame of populist, often statist positions, and reprehensibly included seizing upon vocal racism.
And the latter, yes, certainly was opportunistic, occurring at a time and a generation after conservative southern intellectuals had rejected it, albeit provoking no comparable action among any successful active politicians in the region then or for decades to come.
A few points:
(1) He was a gifted demagogue in OTL, who used divisiveness adroitly to his advantage. The effects of his narrative of his times reverberate today in terribly destructive ways, audibly clashing against continuing echoes of the equally artificial (and divisive) mythology of the New Left; it is well past time we try to rehabilitate either group of horror-show fantasists.
(2) From the 1950s, into the 1970s, Wallace fed naturally off of easily-stoked impulses born of resentment, because he was a cauldron of personal resentment going back into his childhood. He was quite smart, could be very charming and was hard working, but he had drilled into him from childhood that he would never be one of the manor-born elite who stage-managed Alabama politics. He could -- however -- become their puppet, and then develop a relationship with Alabama voters with which to carve out personal independence in defiance of the industrial-legal-banking-state patronage complex in Birmingham.
(3) He began with a social-economic populism, but any POD that would have made a consistently non-racist George Wallace more than a footnote to history would have to begin decades before his entry into Alabama politics. He realized that very quickly and was handed the statehouse for ramping up racist divisive "cracker popularism" in his stump speeches.
(4) Because of the bubble in which they live (even back then before 24/7 faux journalism), career politicians suffer from forms of arrested development, psychologically, intellectually and ideologically. In the mid-60s, Wallace stumbled into national prominence based on vocalizing fears he did not create, but willingly exploited, yet he was not quite sure what to make of those distinct from his now confirmed faith in racial conflict.
(5) However, by 1972 he was finally coming to see that those fears could be separated from appeals against "race mixing." He focused instead on the cultural popularism he'd improvised during the 1968 campaign (e.g., his famous "only two four-letter words" speech about "hippies"). He was still evolving an understanding of how the economic popularism of his youth might in fact be fashioned into a strong plank in 1972, again addressing fears born of the intuition common to those living paycheck to paycheck as to what that decade would bring economically. Studies have shown that Robert Kennedy's own '68 draw included substantial portions of the same working class white demographic that Wallace sought as a national base. Had RFK lived and been nominated, he would have cut into Wallace's electoral vote. Instead, that sector of RFK's support split between Nixon and Wallace. Wallace's extraordinary political antennae picked that up, causing him to run hard in 1972, and to be of some concern to Richard Nixon in the early going. At that point, of course, a fellow wandering around from rally to rally seeking someone to shoot realized Wallace's security was not nearly up to the president's level.
(6) It is a matter of dispute about which I'm not qualified to speculate whether his shift away from the racist rhetorical stance was purely opportunistic, born of maturity slowly developing within the politician's bubble, or a mixture of the two. I will only observe that people are complex. It is also impossible to say definitely whether the contrite Wallace who returned to power in the "New South" was the result of revelations taken to heart from his own suffering and physical disability (which became his narrative). It was, however, consistent with the restless populist resentment of power elites that first took him into politics, and for that reason alone, he remained in a Democratic Party enthralled by the post-McGovern Reforms era.
(7) Whatever inner peace he did or did not find by reconciliation of his past with his present during his final years, it remains the case that his past continues to haunt America. Personally, I think that when Mr. Booth pulled a pistol at the Ford Theater, we likely lost the last best opportunity to avoid a post-Civil War South in the only successful politicians of his era would be what he became. An "alternative Wallace" would have been an unelectable Wallace, and while not purely opportunistic, the last thing he would let himself do was fail. He signed onto a racist populism that had not actually always existed, did not need to exist in his present, and which he ultimately set aside rather than rely upon forever. Yet his declaration at the schoolhouse door remains the moment defining him.
The best that can be said of Wallace's career OTL is that he ultimately brought southern popularism back to its socio-economic roots. But given the ruins he left behind, still haunted by ravenous ghosts, I don't think that is nearly enough to redeem him.
