The Soviet Union was considered on the right side of history by many in the West. The U.S. Democrats has given up on Containment, and were actively looking toward Appeasement. (1)
The most popular cause celeb was the "Nuclear Freeze" movement which would have made the Soviet Nuclear advantage permanent. (2)
President Bush engages with the Soviets more (3) and maybe we get an earlier IMF treaty. (4) No other major changes. Bush wins in 1984. Unless Bush's develops a major following, Bob Dole wins in 88 (5) but loses in the bad economic times of 92.
1) Uh, no. Not even remotely. Unless by "West" you mean West European left wing protestors.
2) THIS was the "Appeasement" movement at the time. But it was only in said protest movements that were being ignored by their governments (except Greece's, IIRC). Those governments (Right, Center, or Left) were being quite mature regarding the "FREEZE" movement, except the British Labor Party. Which was in a state of self-inflicted immolation at the time. The long Thatcher-Major Era wasn't because they were such suoreme political geniuses so much as their opponents were True Believers determined to wait out the electorate until they "came to their senses.".
The key difference between the genuine "appeasers" of the European Nuclear Freeze Movement and their American counterparts was that in Europe it was for Unilateral Disarmament (appeasement). In America, from Ivy League Academia to Hollywood to hard left Democrats all the way over to the American Socialist Party, it was about a Bi-Lateral Mutually Verifiable Nuclear freeze. Ironically, Reagan's "Zero-Zero Option" for the elimination of the American GLCMs & Pershing IIs along with the USSR's SS-4, SS-5, and SS-20 missiles was perfectly in line with that. The American Freeze movement members were simply being the grownups. Oh, and who were the only American Unilateralists? The CPUSA.
3) He CAN'T. Remember what was the reason Reagan gave for not having a summit with the Soviet leadership in his first term? "They keep dying on me!"

That won't change with an earlier Bush. Even after Gorbachev took over, he needed time to secure his political base before he could worry about foreign affairs.
4) Even with a younger stronger Bush, the situation on Moscow dictated that at most an earlier IMF Treaty would be a matter of months, only.
5) I am not so sure about Dole getting the nomination, tho I agree the Dems are doomed with Dukakis. There may be butterflies causing someone else to win the GOP nomination.

Who else might have been in the running when only facing a Senate Majority Leader? Any Governors out there?