>Only thing I am still a little confused on is the external/ internal balance thing.

The balance thing was touched on, but I'll try to help. Before the one piece rear seal on small blocks, the 350 used a zero balance flywheel as the engine was internally balanced. Look at the crank flywheel flange on a pre-'86 350 and you'll see it's not round, but has an eccentric shape that was part of the rotating mass used in balancing. When they went to a one piece seal, the crank flange had to be round so the seal could slip over it. As a result, the eccentric mass that was on the flange of the old crank was transfered to the flywheel, thus the engine became externally balanced. So, you need a flywheel for the one piece seal crank. The earlier flywheel won't fit anyway.

Bob