I honestly don't think it would matter who is starting with him. I mean Kobe starts with Nash, Gasol, & Howard yet still manages to get over 20 shots. That's Russy game too, he is going to be aggressive either way.
Really Perk is the only starter we need to replace. Need Thabo for defense & need Martin for the bench to be productiveThat's why I would rather go after Marcin Gortat or Al Jefferson than Varejao (plus Varejao is always hurt). But with either of those trades we would still be better with another bench scorer/shooter.
Al Jefferson is the best fit for the Thunder, Gortat has solid numbers but he relies on the PG to create his offense for him. I think Jefferson would fit almost seamlessly into what the Thunder do because all you really need to do is pass him the ball on the block and he'll create for himself.
It's much easier to take Gortat or Varejao out of the game than it is Jefferson, both rely on the pick and roll and Big Al just gets the ball on the block and goes to work. Can't go wrong with any of them, but Jefferson should really be the number 1 target.