The two I posted for V6 cars are about the best out there.
You can also try http://www.t6p.com and http://www.gnttype.org
I'll tell you this much, if you're planning on building a motor or a transmission, make sure whoever does it knows what they're doing when it comes to Buick V6s, clearances are not the same as a SBC even though a lot of builders tend to think so. The 2004R is a rare breed too, there are two guys within 2hrs I trust with building them, that's it.
You can get a hot air motor cheaper, and it's basically the same thing. Heads, cam, pistons, rods (assuming they're 2 dot, but as far as I know all turbo motors were 2 dot, though someone has said otherwise...) crank are all the same as the 86-87 motors. The difference is a hot air motor doesn't have an oil return drilled into it and they have 14 bolt oil pans instead of 20. The front cover is also a little different, but nothing major.
Then you'll just need headers and intake manifold up from an intercooled car.
You can make ~500whp on stock internals without having to worry about much. Depending on weight of car, if you go with a 2004R at that level you may or may not need a billet input shaft. I'll be shooting for around there and I'm running a stock shaft. I'm hoping the car is light enough to not twist it, but that's a risk I'm willing to take.