New heads/intake/rear end
You can build a Spooled Dana for around 1200 with some frugal shopping.
For a little more than the 1500 you can also get a Strange or Moser Dana 60.
Call this guy, Cass, and ask if you can get one without the snubber provision. Might save a few bucks.
http://members.aol.com/doctordiff/dana.html