Anytime I am adding anything to my crankcase that is not oil I get paranoid. Ok with ZDDP but other than that I stay away from additives. Like you John I am in uncharted territory. Right now the mtr has new oil and filter with Lucus ZDDP, zero miles. Just a startup after the change then turned off.
Partner at this stage of the game if you have another bearing(s) going bad it really does not matter how many times you flush it or what snake oil you use to flush it with.
A bad bearing it just that - bad. That being said I have torn down engines that were running fine that had bearings that were totally shot.
Drive it, if/or when it fails replace it with your other engine.
Good luck and happy motoring.
