What I can say is that I'm the one that tore mine down up front and I'm glad I did. On the other hand even after doing it, I would do it again regardless just for piece of mind if I was to do it again. If you look at what you get for the money you can afford to take it apart and clean things up and your still money ahead for most comparable aftermarket builds. I've got a good engine in the 120R for $4200 + about $400 more to tear it apart and clean it up. So for some of my time and $4600 I have a well built 120R with a trued, welded and plugged crankshaft. Where you going to find that from the aftermarket engines?
While I wish you could just bolt it in and go, some are having issues and others are not. With my luck I would have been in the having trouble group. For what it's worth my factory run out was .0005" on one side and .0008" on the other side. Once the timken conversion and crankwork was done I now have .0004" and .0005" so I'm happy and I do not have to worry about it changing anytime soon.