A heavy load of spray soap like Simple Green and a ball hone. Spray the soap as you hone till the foam turn white and not rusty. Rinse, dry, and wipe with a wad of paper towels soaked in WD40. A large wire brush in a drill will also work, just not as fast as ball hone will.
When I start an engine build for customers, strip the block to bare casting, no plugs of any kind, then sandblast the block, wire wheel, cut off any flashing and soften the sharp edges, then degrease, then power wash, then hone, then power wash again before sending it to a machine shop. I have them jet wash it when they are done, then I wash again with degreaser and scrubber pads. I use commercial floor polish pads cut into circles clamped to a threaded rod spun in a drill to clean the bores after machining. I also use scotch bright scrubbing pads cut into pieces pinched onto long welding rods spun in a drill to clean oil rails and lifter bores. Every bit of the blocks has been scrubbed or wire wheeled before assembly. They look like fresh cast blocks when I start to assemble.
joe
