The works is not something I would use for a bore. If it was heavily rusted, to see what is left, Phosphoric acid is a good way to remove every trace of rust. Coke has it to add tanginess. Hydrochloric acid works much faster than phosphoric but every bit of it will have to be removed and it is difficult to do so. Also, when de-rusting objects, it will combine with the good metal and cause surface embrittlement. Which is not a good thing for thinner metal objects. Phosphoric acid does not do this and leaves a phosphate coating behind. Chrysler (probably others) dipped their car bodies in the stuff prior to paint in the 1940's to prevent rust. Rust is hard to stop in pits. This will do it. Obviously the bore has to be lapped afterward and of course really bad pitting will catch on patches, and it is a ruined bore from the rusting anyway.