Goodwrench Targetmaster specs Anyone know them?

[70LongbedC20]

ID on Pad: 10066036

I know this is a "Hecho in Mexico" 350, 2 or 4 bolt mains, etc. I also know they often came with crap 76cc chamber heads. But can someone tell me what the compression, power output and camspecs on one are? I have more heads, wanted to know if I could just swap to a smaller chamber/bigger valve head, or if a cam change is also in order. Runs smooth. Just need the truck to tow my Chevelle, but as usual I can't resist trying to make it faster all while trying to retain decent gas mileage.

I've heard some people say that these block are crap, but many others have used them for years without problems. Just wondering if anyone bought one of these high powered puppies and has the specs.

Thanks