My money's on '92 Pantera.
UK spec was mostly LX, (front and rear mechs, shifters), 500LX cranks, Deore cantis and 'Shimano' hubs (no other markings), with Ritchey Vantage Sport rims. Original stem looked the same as the flip-flop, but wasn't reversible. I can check the serial of my '92, if...