Jack,
You have to use a flywheel or flexplate that is made for the one pc crank. It will have a weight on it, similar to the 400 small blocks, but not the same. The reason for this is the fact that when they started making the one pc seal crankshafts, they had to do away with the "oblong" shaped crankshaft flange, which was actually a counterweight of sorts to help balance the crankshaft assembly. Otherwise, all of the above information is correct.
You have to use a flywheel or flexplate that is made for the one pc crank. It will have a weight on it, similar to the 400 small blocks, but not the same. The reason for this is the fact that when they started making the one pc seal crankshafts, they had to do away with the "oblong" shaped crankshaft flange, which was actually a counterweight of sorts to help balance the crankshaft assembly. Otherwise, all of the above information is correct.