You have an option here.
If you plan to polish the valley and improve
oil return, do it NOW.
If you plan to open up any areas or put restrictors in, do it NOW.
If you plan to polish or smooth the block, do it NOW.
Anything you want to do to the metal, do it NOW.
After it comes back, all shinny and new looking, then you can tape off things and paint to the cows come home ( or sooner ).
If you remove all of the bumps and casting trash from the outside, the paint will be smooth and shinny and look like it was dipped in plastic...if that's what you want.
