Tim, you could restore the "desroyed" engine for not that much money. It really depends on how severe the damage is. If the groove for the woodruf key in the crankshaft is worn out you could replace the crankshaft for about $100, $10 for the gaskets and $15 for a workshop manual. BTW you'll need to have good tools too.
The main reason why those woodruf keys destroy themselves is because the flywheel wasn't mounted propperly. If the flywheel could rotate on the crankshaft even just a fraction it'll destroy the woodruf key, the flywheel should be rigidly attached to the crankshaft.