cups screw in and out just fine, and oldschool did not make any mention of the bottom bracket threads being dodgy( make of it what you will), once the BB is in i cant see there being a problem, drive side threads are fine, though again i havent ridden the bike, as a hack you could always be double sure by using locktite , i dont think anyone gonna spend the money taking this frame to be rethreaded, and worse case scenario is having to use a threadless bottom bracket,
if you want it, we can call it £20 posted, which leaves change for a new bottom bracket if it sheers, cant see that happening though, its non drive side and there are threads there, just not great ones