Yea that works just making sure you don't have any grease or flaky paint on it and not sure if your taking all the paint off the block and if not sand the paint with a scratch pad.
Paint reducer works for cleaning before painting the block and Alcohol.
Only time you might have problems with paint on an engine block from what Iv'e seen is on the freeze plugs. a smooth surface and sand them with a scratch pad even if there new.