sandblasting engine

Save the sandblasting for individual parts and pressure wash/oven cleaner/pressure wash/oven cleaner the motor to get the grease off. The oven cleaner _should_ get rid of all the paint that's still sticking to it but if not, get an aerosol paint stripper and it should bubble everything else up. If it has surface rust, use some naval jelly (goop it on fairly thick with a brush or an old rag) and let it sit a few hours, then pressure wash again. That should basically leave you a surgically clean engine block without ever blowing sand at its sensitive guts. It's time consuming, but if you want it clean, you can either do it slow with very low risk (elbow grease), do it fast with lots and lots of work (tear down and hot-tank), or do it fast with huge amounts of risk (sandblasting). Soda blasting might be an option if you have a cabinet big enough to fit the block in. It washes clean and shouldn't leave any grit if you're careful.