fwiw, i have a relative who wanted to do the same swap into his wrangler. he ended up with a 4.3 swap, because of all of the electronics that are tied to our beloved 3800.
as for mounting locations, this is going to be one heck of a custom job, so i wouldn't know how much it'* really going to matter anyway. by far, your best bet will be to grab a 3800 off of a camaro along with it'* PCM and tranny. then you have your RWD tranny, less PCM funkiness, and you can still get it in a series II.
just my 2 cents...
96 LeSabre (L36)
95 Olds LSS (L67)