The minimum changes would be crankshaft, camshaft, harmonic balancer / vibration dampener, flexplate, and distributor. Think the rods are different also. The intake still fits, but probably now has flow imbalances by design. So what do we have left, just the block and heads... Sounds loke a SEVERE waste of time and money.
Yeah, the whole rotating assembly needs to be changed out and the even fire heads from what I gather flow better. The distributor just needs the pickup coil changed out.