you think #8 walls are cracked or just heavily scored? If your block has value to you, can you just sleeve it? I have a sleeve in my #7 due to a wadded up piston and broken rod prior to my ownership. luckily the crack wasn't at the very top/bottom of the bore which you may not be able to sleeve. It was easier than sourcing a new used block and going through all the evaluation and machine work again.
If your other cylinders are in really good shape maybe you can save money there by not doing any machining or overbore.
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