many thanks for the reply, and would you believe it, 5 minutes after i joined up somebody put 'breaking complete gpx250' on fleabay. i got straight onto him and he said it was good condition, so i sent him what i thought was a reasonable price. then he gets back to me saying there's a bloke going round in the morning for a load of bits, but he doesn't know if he wants the tank. go figure. i thought i asked first? whatever happened to chivalry? anyway, the later tank, having looked at it underneath, i was going to put a blanking plate over where the tap should go and attach my standard gpx tap to that, which SHOULD clear the frame tube if i mount it right. btw, frame has just been powdercoated, so i don't really want to start cutting/brazing on it again. but thanks again, i now have a plan 'b'
cheers, dd.