If anything, i believe you will be ahead of the game to thoroughly check and clean any aftermarket block just as we do to a stock block. It is preventing any chances of contamination….i guarantee that I can find some grit, shavings, etc in any block if thoroughly checked. There are just too many spots/ crevices for something to remain.
I found some very small amounts of material in an Indy maxx block a few years ago and will check a mega block from ‘06 just as thoroughly when the time comes.