Glad to see your making a plan.
I also like the idea of a 200R4. Only a few bad things about them. Made for just a few years in the 80's, most were behind really low HP engines(weak). GM did build some up for the Buick GN's. The one shop I recommend is The Real Art Carr.
http://cpttransmission.com/ I also like a 1800 stall. Your not making a racer, but a great driver.
I prefer the single exh. Bring 2 pipes from the engine and join them somewhere under the driver, a BIG muffler and a 2.5 tailpipe. I have a big muffler on mine and it is still louder than I want it to be. Easier to pipe under a car also. Mine can make enough noise to make a kid cry.
