What about the old school 3/8s offset ground stock crank,chevy 7.1 rod,custom piston = approx 470 CI. No welding req and around 2375 bobweight. That was one of the old school combos built in the 90s by a local builder here in VA and may be cheap to build today IF you could still get the pistons and the crank work for a fair price. Its kinda hard to beat the price of avail kits these days.