Kirk, there's usually a set or two kicking around in the classifieds and much debate about whether or not the cracks will ever amount to much, other than an annoyance. That being said, you could buy a set of EQ magnums with the LA bolt pattern new for like $650 a set I think off eBay...or just buy the bare castings and have your machinist put them together
Honestly though, find a running engine out of the yard that has good compression and buy them