I don't know how well your shop cleaned your engine but I would take it out on the driveway and wash it with some Simple Green and a pressure washer and clean it out good inside and out. Use a rifle ram rod with a cloth patch to clean the oil galleys. Make sure you get All the leftover metal shavings out, or your going to be rebuilding your engine again.

Once it's clean of all dibris and oil you can paint it. Block, head, oil pan or what ever strikes your fancy.

Hope this helps
George