[GreenLS6]

Used to build alot of "781-049" big oval port Large valve 454 and 489 ci Motors for people, 15-20 years ago. Used the TRW Ls6 replacement piston (or speedpro equiv ), 3/8 truck rods ARP rod bolts, cast or forged crank ( Cast 8lbs lighter plenty strong and cheap) with felpro Blue .041 head gasket. end up true comp. 9.8-10.1 range. You do have to releive the edge of the chamber about .030-.040 thou.. Hits very edge of dome on some heads due to core shift( always check!!!)

The 489-496 motors I would mill about .085-.100 off the deck face of the piston(not dome) to acheive a postive +.005 out of the hole, then run the same .041 head gasket for optimum quench of .035 thou. then run the Comp cam 288AR solid roller .623 lift. Super torque and almost 600hp. <span style="font-weight: bold">CHEAP!!!!!</span> Street monsters