Back in the late 80's I raced a dirt car with a 300 in it. I had a forged crank that came out of a truck. We used 351W 4 barrel pistons (flat tops). The 351W pistons were stock bore and the compression height was the same or darn close. Some guys used 390 4 barrel pistons but that required boring the block. Some guys turned the 390 pistons because the 300 doesn't like a lot of over bore. At least not in oval track racing. Mine had SBC Total Seal rings, a solid lifter Crane cam. Don't recall the cam specs for sure but I think 284 duration with .586 lift. I used a 300 head but if I had it to do over again I'd use the closed chamber head. Pin the rocker studs as mentioned earlier. Crane made roller rockers for the 300 but they are tough to find. I had the head ported, bowls cut a lot bigger, and stainless SBC valves installed. Don't recall the sizes but as big as we could go. Also had a 5 angle valve job. I used an 4 barrel Offy intake but the Holman and Moody piece is far superior if you can find one. I used a Ford electronic ignition with the advance plate welded up. The Ford ignition box I used was the limiting factor on that motor. It wouldn't rev much over 5800. An MSD box would have allowed for more RPMs but then I would have had to upgrade the rods and bolts. As I recall a SBF flywheel will bolt up but you'll need to get it balanced. You can weld an arm on a SBC fuel pump if you can't find a good pump for the 300. The 300 is a torque monster. Could be a lot of fun on the street. Oh yeah, the 240/300 eats water pumps like candy so carry a spare.