any point in working on a big mans PE rating if he’s only going to get to 40 or 50? Obviously he won’t be shooting 3s but it seems logical that it would improve his mid range jumper correct?

You right that for a big man, the interior skills are more important. But I would say perimeter also matters, especially if you are talking about 40 to 50 then you can position him to -1 on the 3pt. Player Game Plan and that can make it more difficult for opponents. Certainly if you capped on potential in the other skills and PER has room to grow then you should.

Perimeter helps with scoring....even two point shots