By far the hardest part is actually getting the Indos to West Papua. They were not an agricultural people, by and large, nor was there any convenient pre-existing state apparatus for them to insert themselves into. You'd probably need an earlier PoD, or a much more extensive (expensive) program that included other Indonesians, in particular the sort that Jakarta has succeeded in throwing at West Papua since 1960. If that can be achieved then a bunch of name changes are quite plausible.
Uniting West Papua with OTL's PNG is almost just as difficult, unfortunately. Contrary to what is occasionally peddled in Western circles, there is no real cultural affinity between the West and East of the island. Indeed, there is very limited affinity between the North East and South East, and obviously between the mainland and the islands to the east. PNG has only survived intact as that has been in the interests of other states, in particular Australia. Uniting it with West Papua is not impossible, but would almost definitely require even more Australian support and would likely today have even weaker state structures. The existence of an educated Indo community is unlikely to help, as you'll either end up with a bunch of separatists who want to form their own small state or they'd become the resented proxies of Australian/Commonwealth government(s) that form the ruling class and are hated by all the others.
Actually, the plans involved also bringing of Calvinists Dutch farmers directly from Netherlands. How many of them might have immigrated? It was planned that the Dutch cultivate lowlands and Eurasians highlands.
I don't wish to bring in other Indonesians. Actually, the Eurasian relocation plan was formed in the 1920s:
"1923, the first plan to designate New Guinea as a settlement territory for Eurasians was devised. In 1926, a separate Vereniging tot Kolonisatie van Nieuw-Guinea (Association for the Settlement of New Guinea) was founded. In 1930, it was followed by the Stichting Immigratie Kolonisatie Nieuw-Guinea (Foundation Immigration and Settlement New Guinea). These organisations regarded New Guinea as an untouched, almost empty land that could serve as a homeland to the sidelined Eurasians. A kind of tropical Holland, where Eurasians could create an existence.
These associations succeeded in sending settlers to New Guinea and lobbied successfully for the establishment of a government agency to subsidise these initiatives (in 1938). However, most settlements ended in failure because of the harsh climate and natural conditions, and because of the fact the settlers, previously office workers, were not skilled in agriculture. The number of settlers remained small. In the Netherlands proper, some organisations existed that promoted a kind of "tropical Holland" in New Guinea, but they were rather marginal. They were linked to the NSB party and other fascist organisations."
If by 1950 say, 10,000-100,000 of the Eurasians, rather than less than 500 that were there then, were already in WP, and another 60,000 came between 1950-70, would that be more realistic? To make them get there, let's say that Netherlands refused to admit them in but financially assisted emigrants to WP, and that Australia and US refused them too but aided Netherlands in organizing the relocation.
The federation would've came into existince, as the article and other sources say, among other reasons, because with it Australia could relieve itself of administering PNG and mane sure it never joins the Australian Commonwealth. Also, the indigenous Melanesians won't be consulted about it, so their affinities or lack thereof would've been ignored.
Eurasians would be divided politically into federalists and separatists pushing for an independent West Papua. They surely would form the ruling class, and serve Australian interests in keeping Melanesia together, arousing anger of separatists everywhere (my Melanesian Federation is the broadest proposed one, including not only WP, PNG and SI, but Fiji and New Hebrides, where Francophones might be separatists from the Anglo-Dutch dominated British dominion).
