I'll second the 3.9 or Pentastar. At one time I also had the wild idea of a complete 3.5 LH platform drivetrain and suspension in an A-body. I grew to dislike the 3.5 enough that it's an idea that I have long ago abandoned...
That looks pretty good. I've got decent top plates for my Barracuda, but I have this crazy idea that if I had a CNC mill I'd do a one-piece top with engraved shift indicator (maybe with lights) and a pair of cup holders back in the glovebox area.
You're keeping the front drums? I don't think that's advisable, but I do have a complete 10" front drum set out in the shed. Plus, I think most of the parts may be available new.
Yeah, it's pretty straight. I haven't looked under the carpet yet, but it does need soem trunk repair and slight quarter panel repair, but it will be one of those "easy restos", sort of.