We deal with alot of mairine blocks on my area and we have sonic tested quite a few of them and have not seen the cylinder walls any thicker then any other stock 454 block.Marine blocks have thicker walls to help them stay cooler. Yes you can run them in your car. I just bought mine, A marine 454 that my brother built, Bored it 100 over & stroked.
Gives us around 596ci Will be fuel injected with an old Hilborn style injectors, backed up with a 4L80E