Swapping a ring gear is easy. Knock it off with a hammer and punch or chisel. Flip the flywheel upside down on a metal barrel. Heat one side of the new ring gear with a propane torch and drop it on. Tap it down with a brass punch if it didn't drop into place. You can tell when the gear is hot enough when a couple drops of
oil go up in smoke next to where your heating it. Same procedure for bearing races.