If you want a hotrod 6-cylinder, do yourself a favor and start with the 292. It's much more fixable than the 250, and you won't have to stress it as much. I raced against one on a 1/4 mile dirt track for several years, and he could out-torque my 327 easily. We were running open-wheel Sportsman cars in northern California, and he was a consistent winner, even competing against the V-8's. He spent about twice as much money on a competition buildup as us 8-cylinder guys, though!
Jerry