Ultra desirable
Come 2 or 4 bolt
Come 3.91 bore, have seen them check good for use at 4.125 bore. But each one can be a bit different. So, to get to a standard 4.04 340 bore, need lots of metal removed and sonic checking, imo, is a must
Beefier bottom end, filled pan rail, etc
Standard 340 type top end, so unlike 59 degree r3 blocks, roller lifters drop right in.
They can take a lot of punishment. They are my favorite LA 59 degree block
I Ran one at 4.100 700 horse years ago, that block is still in use
Virgin block like you have is worth 3k + all day