My engine builder has a shot peen cabinet and a tumbler. On all of his higher end engine builds, they are hot washed, shot peen'd and then tumbled clean. I must say that the blocks turn out great. I was so impressed I asked him if he could do my 610 intake for my 68 and ho obliged.
It turned out great as well. I'll see if I can find a picture of my block when it was cleaned. Here's the intake before I added the correct M intake bolts.
