[chopper]

I think it's highly unlikely that the main problem had anything to do with the expansion tank leak. The tank leak should have just blown coolant out through the rupture (at least, that's what mine did). It should also be unrelated to the distributor seal. Your planned course of action is logical IF you have found some of the head bolts loose. Then it would make sense that there may be a leak around one of the gaskets and the problem may be resolved by merely tightening the head and intake manifold bolts. If none of the head bolts were loose, you might want to pull the heads anyway and check to see if the head and/or intake manifold gaskets are damaged. My 2 cents worth.