What imbalance flywheel??

What imbalance flywheel does a 1980 flat tappet motor use for the flywheel??
Also- What would happen if you put a 50oz flywheel into a 351w ?
Im not about to do it or anything, im just curious..

ALso- the most important thing is- WHERE CAN I BUY A 28oz Flywheel for a t5 !!!!!
cheapest price wins 5$ on paypal.