Turbo/Forced Induction

So its been a while but i'm back. I sold my Barracuda but still a mopar man.
I do have questions on another love though. I just don't know where to go.
So I have an 89 Buick leSabre with 3.8 liter auto trans. Its Grandma's old car. Its torquie though and the speedo says 85 but it does better than 85. :D
So I've had thoughts on building it and turning it into a sleepier.
Plan, Scrap yard get motor and trans from another with compatible motor, 3.8, and trans.
Build it to handle 40 to 60 lbs of boost. So, forged internals, iron heads, and cross mains but i don't know if i'll need cross mains.
And rebuild the trans, like a racing trans but i don't know what that entails.

Anyways, i'm seeking advice as to what i should look for in a transmission and if it would be possible to take the ECM designed and mapped for a Grand National and use it in place of mine. Or if I should get mine who car tuned professionally to preform properly.

I have just about no idea of what i'm doing except the building of the motor, and machining to make my money lol.
I just think it would be a lot of fun to pull up to a stop light and roast the new bmw that came off the lot.

Thank you all!