I bought an 84 Blazer that had a similar problem though not as bad as that. Holed out and cracked length ways. I used a nut and bolt like what you had and drove the K5 for years before the compression went away. I got plenty of use out of that 800.00 bucks.
There is another option.
6.2 Engine blocks do not have a robust reputation. The best blocks are 1982 red blocks. But the heads are one year specific because of injector threads.
I like Detroits but the 6.2 has to be the most crack prone of them all. I would not even consider that a repair but...
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