Cleaning rust from water jackets.

[40cpe]

I had a block dipped at a former Redi-Strip franchise. They don't go by Redi-Strip anymore, but are a commercial/industrial metal cleaner. When I got the block back I could see that here was some rust scale in some areas of the water jacket, while other areas are clean. I chucked a piece of 3/8" stiff guy wire in my drill and went into all the holes around the cylinders. Then I used a piece of stiff steel wire about 1/8" and went in between the cylinders and the exhaust passages. When I turned the block on its end there was a double hand full of rust and scale fell out. I'm confident I can't reach any more with the limited access but I know if I got this much out there is more. What is the prudent action to take? I've read good things about Evapo-rust and am considering putting the block on the engine stand so I can level the deck, block the water pump holes, and soaking in the Evapo-rust.