MFA used to do nice Olympus 2:1 toothed belt drives, but no longer. I have a set in a Rother class, nice engine Sound. SHG models sell the belts and pulleys, had thought of those. Also there was one on direct drivefor sale on here, I asked what the motors were and got no reply. if I get it wrong I can reduce the speeds on my Spectrum transmitter to compensate.
back to the drawing board for me thanks for the info I'll let you know what I decide I can start building its not a problem, at the moment I'm half way through building the Euro Girl so got plenty to do and it will soon be Christmas.