So your problem is with the mains or the seal, not the rods. I don't know how you shimmed the mains but usually they are done one at a time, with it loosened after fitting while work continues on the next one. Sometimes when they are all done up after, the crank won't turn. To me this indicated an inaccurately aligned bore. I experienced this on my truck 216. I found out which main caused the problem, added some shimming and all was well. That was forty thousand miles ago.
