So first off this is vato1971 this site wouln't let me back on as that user and I couldn't get tech help so this will now be me. Moving forward, of course a chevy 4.3 anything else would be silly and yes they did put them in a G body stock just not the Regal. They were in the 87-88 Monte Carlo with a 700R4. The buick has a universal TH200C so I can bolt it right up to the trans the problem lies in the fact that the 3.8 has the mounts all the way forward on the block and the 4.3 are about 3-4" back so the trans is either going to need to come forward or I will need to move the motor back. So this is a V6 to V6 swap just not as easy as I thought it would be. The buick engine is the oddest thing i've ever worked with even weirder than my Rivieras 455.
Thanks for the posts people I will be working on it this weekend seeing what to do.