Jordan
JUst double check what diff you have in the MG Metro gearbox. Bill Richards recently rebuilt my MG Metro engine and gearbox and I'm sure he said they had a 3.7 dif as standard as they ran on 12 inch wheels.He changed it for a 3.44 and it gave better cruising speeds and I'm still on 10 inch wheels. I'm no expert so it's not gospel but I would just double check if you're going to that effort.
that interesting i will be doing bulk rings and other worn parts on it so will check when i have got it all apart cheers for pointing that out.
regards
jordan