What happens to the most gifted proles in 1984?
I could not find any mention about the most "gifted" proles as such, but the author does address what happens to those proles who are are judged "capable of becoming dangerous". A few agents of the Thought Police do move among the prole population, and when they detect someone whom they think might have the potential to become "dangerous", they mark them down, spread false rumors about them, and eventually eliminate them.
The general Party line is that the proles are
"natural inferiors who must be kept in subjection, like animals...left to themselves...they (are) born...(grow) up in the gutters...(go) to work at twelve...(marry) at twenty...(die) for the most part, at sixty...heavy physical work, the care of home and children, petty quarrels with neighbors, films, football, beer, and above all, gambling (fill) up the horizon of their minds".
It is clear that the Party believes that the proles are easy to control because they are unintelligent, and, knowing this, I think it would be safe to say that those who are deemed potentially "dangerous" would most likely be those who somehow show more initiative and understanding of things than the rest. In this sense, they might be considered the "most gifted", and capable of becoming dangerous to the Party. As noted by the author, these proles are systematically "eliminated" by the Thought Police (Part 1, Chapter 7).