dungeon, your solution is rather simple to mend. Just go to the local parts store and buy a flex plate that fits a 89 car like yours, for about 50 bucks, then take the entire rotating assembly to a machine shop to have it balanced. The crank, the rods, the pistons, and the rings, plus the balancer and the new flex plate. He will charge you about $150 and you have a banaced motor good for 8000 rpm.