Search on www.slantsix.org. There is a group (or other site) dedicated to the aluminum blocks. At one time they paid for a group manufacturing run. Will be costly, so pull the head first and see if yours is even salvageable. I read that often the parts are so corroded that you can't resurface by milling, but don't let that scare you. Cool if you get it fixed. I would love one of those engines.
I will stand by and argue the point that any of these engines cannot be repaired. Aluminum is dead easy to work with. Any certified welder worth his salt could make one good as or better than new.
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