Cleaning 383 Block

Hey all, so i stripped my 383 block all the way down and I want it cleaned really well before I put it back together, a local shop said they have a spray booth and he leaves it in there a few days and it sprays a special water chemical substance in all the holes to clean it up, he only wants $100 for, and I'd be fine with that but I'm unsure how well this will clean it. Does anyone have experience with something like that? I tried to find a shop that had a dip, but hes the only shop that is close that has anything and I don't feel like shipping the block. Thanks.