Santucci mentions drilling out the 7/16" old flywheels to accomodate the 1/2" bolts in later cranks. He also mentions that some drill out all the dowels and tap the holes for a total of 9 flywheel bolts if you are running a 4spd, but if you are running an automatic, you can leave it stock without worrying about shearing anything off. Apparently some racers experience problems when cranking 500 - 600 HP through only 6 bolts and a couple of little dowel pins when grabbing gears on the drag strip eek Santucci also mentions that crank balance should always be "zero".

I know a guy "Walt Skoczylas" that I have worked with who has a methanol fueled 292 w/6-71 blower who does ~8 second quarter miles. He claims the crank shaft is the last thing to worry about as far as these motors are concerned.