Hi Paul, if it is any consolation, I had the roller bearings distintegrate on one lifter - it left tiny bits of them all over the engine !
Net result was a full rebuild (the one I was going to have anyway, but hopefully some years in the future) - the block & heads were ok, but new 331 crank, pistons, rods, bearings, oil pump, sump, cam, lifters, pushrods went in.
At $8,500 it wasn't cheap, but I ended up with a much stronger engine which is now a "known quantity" - I am happy (unlike the bank manager) !!
Good Luck mate,
Kind Regards,
Peter D.