wow i did not know this i thought you could knife edge the crank if that happend. i think my crank is fine the problem with the motor was a burnt valve.If you spun a bearing you can throw your crankshaft in the garbage, it cannot be machined and even IF you had it machined you will end up with excessive clearance in the rod bearings. No bearing will help you here and no machine shop can cure it for you. Not even god. As for what you said about the bearing surface being flat, I think you mean't to say "smooth". If you have ever seen a rod bearing...well...you get the point by now.
how the b18 and b20 blocks are the same but honda made a diffrent sleeve for the b20 because they were trying to get 84mm. i know with iron sleeves i can bore it out maybe 1mm but thats recommended for all motor not forced induction. sounds like the sleeve is getting really thin i know the sleeve will handle it but its not worh the risk.You want to sleeve something sleeve the b20 and go bigger then 84mm