Q: I want to stick a SBC/BBC in my Regal, what do I need?
A: This is a fairly common swap and there are several Chevy oriented forums out there (including GBody.org) that have a lot of info on the swap. We highly recommend carrying the discussion to those forums.
Since the focus of this forum is Buicks and Buick Power, we don't really discuss this type of stuff, just to keep the clutter down a bit. An appropriate topic would be the swap of a Big Block Buick into a Regal ... there are several folks who have done that with great results.
A short answer to the question would be that the SBC will need bracketry, accessories, Chevy transmission with corporate or Chevy bellhousing pattern, motor mounts, fuel system, etc. A THM350 is common to the platform, so depending on the donor car, it could be a very easy swap as far as crossmembers and linkages are concerned. For some visuals on the THM350 vs. the 200-4R, look here:
http://www.gnttype.org/techarea/pict...m200vs350.html
It appears that a THM200C and a THM350 are very similar, but the 4R is longer.