I’m wondering if you can fit a road/ CX bb30 crankset into a bottom bracket she’ll that’s originally for the Shimano PF82 (I think) system; there must be some kind of adapter out there??

crank is too narrow. You can do it the other way (std crank in a BB30 frame) but not the other way round.

Ok, thanks.

If you ignore the spindle length for a moment, BB shell ID = 41mm, that leaves a bearing that’s 5.5mm deep which would require tiny ball bearings that wouldn’t last very long. The fact that the spindle is 68mm long fitting into a 68mm wide shell further complicates things. Only 30mm spindle crank that would fit is Rotor or FSA BB386 both use a longer spindle leaving room for external bearings