Pick them up! The blocks seem to be stronger and even the old (pre 09) castings can be made to flow over 300 cfm. You can buy the newer 09 5.7 heads that flow 300 cfm right out of the box for 600/pair complete with iridium plugs. They will accept a 4" crank.
Tom

10.56 at 125.6, with a 1.43 60 ft. E85, Hyd. Roller 410 magnum,full exhaust, 3500 race weight.