74 318 crankshaft

Have no clue on balancing what the difference between internal and external balance. I was not there when engine was balanced all I know is he needed my balancer crank and flyWheel. . Flywheel I got is a 440 source wheel. So my 4 speeds has the center force dual friction clutch can I just get an OE flywheel??? Also have a number for those adapters I've herd of them but never seen em. Does it eliminate the bushing or is it tied in with adapter.??