I ended up snagging a clutch master and slave cylinder when I got the engine, hoping they were good rebuild candidates since new parts are not cheap at all. The pistons in both move freely, which is a good sign. The clutch slave seems to be pretty new (as is the hose I got with it, also not cheap). The cylinder bore looks pretty good. Couple minor scratches but I think it'll hone nicely.
I can't even get the master cylinder apart to inspect the bore. Seems like there should be a snap ring or circlip to remove in order to withdraw the piston, but there isn't one immediately obvious.