Some replacement main bearings have copper on the thrust surfaces, others have a babbitt plating. Did you notice which yours had when you installed them? Their present color might be "normal."
I don't see any reason you can't use the rings you have. I would remove the pistons, wash everything thoroughly, then oil the rings and wrist pins when you install the pistons.
Too bad you have to lose another .010" from your crankshaft. But I guess that gets into the category of 'good insurance' for the job. And you will know you haven't taken any shortcuts that may haunt you later.
Harvester
