Come on, are you kidding me? Camshaft technology is THE most influential factor in the power output of an reciprocating engine. Lots of good cams are available for turbo buicks, so I won't enumerate here. You have the intake and exhaust capability, so why not use it? I like the folks at Poston, and they sell good cams. Give them a call, and theywill be happy to talk to you. Good luck in your quest!
Do a search on stock cam and you'll find that some members have been as fast as high 10s with a stock cam. Also, most will say that the stock cam is the most reliable unit. So, if yours is still good, it would be best to leave it alone. Remember, this is not a chebby engine we're talking about (no offense to you Chevy guys). My cam had had it (after spinning the #1 rod bearing, so I replaced it with an aftermarket (during my rebuild), but would have gladly used a stock cam if it was still available (new).
Probably no gain with the stock heads over a stock cam.
Unless 83TT can show me how much better a Poston cam, or whatever it is, can provide more HP in your situation, would have to say head flow is more influential. Done many head upgrades with significant improvement in performance. Cannot say the same for cam changes
I agree with Nick. There is probably very little if anything in a cam change with stock heads. Much has been written about this very subject over the years. I remember Jim Bell writing about this very issue. He said that because the 3.8 turbo makes it power over a very narrow rpm range it becomes a cam grinders nighmare. Coventional thinking doesn't always apply to a forced induction motor. My turbo Regal was able to run 10.7 with head work but with stock cam. TE 34 was the turbo at that time and it ran 124.96 mph. That is not to say that aftermarket cams do not work. Heads make the big power increases on Buick turbo motors.