How clean does the gasket surface between the head and engine block have to be? Gasket came off pretty clean and I've used cleaners and a razor blade to carefully clean off all remaining gasket. It's definitely smooth to the touch, the head is pretty much back to the original surface but the engine block isn't 100%. Still some discoloration but very smooth. Should I use wet/dry sandpaper (200+ grit) or something else to finish the job or is it good enough?

400 - 600 grit on a piece of glass
R/

seabeelt wrote:400 - 600 grit on a piece of glass
R/

Ended up using 400 grit wet/dry sandpaper on a smaller ceramic tile (didn't have any glass available). Was really careful to keep it flat and now it looks really clean. Just waiting for head studs/nuts and then the head goes back on.

I usually use a sanding block, some use a wetstone. Under no circumstances use the gasket removal discs on a die grinder, they are OK for valve covers or similar, but not for anything that must be perfectly flat.