I am looking to buy a supercharged V6(96 or newer) from a Park Avenue, Bonneville, Regal or something of that sort. I want to put the engine into a E36 BMW. Since the Buick engine is transverse mounted, would that cause me any problems. Have any suggestions?
I would not advise it. Buick did the same thing in reverse in 1985. The 1985 231 transversed V-6 was the same engine used in RWD cars just twisted sideways. They had a noticeable main bearing knock although it didn't cause any problems. The engine was changed in 1986 to fix the problem. You would be better off getting a Buick V-6 from a Camaro or Firebird and adding the supercharger to it.
Even though there was a main bearing knock when Buick did that in 1985, I don't see how there would be a problem like that using a new engine.
There is something strange that happens when you turn them 90 degrees. That was one of the main reasons the counter balance shaft was added in 1987. There is no book or info that will answer the question 100% It's back to the trial and error method.