I'd love a '77 TM125.
The engines seem to look very similar to a YZ125D engine from the outside - it wouldn't amaze me if they're based on/copied from the Yammie motor, which wouldn't be a bad thing.
Is there really any choice ?
....
Actually, I do recall a bloke on a 175,
Enduro CanAm faring
very well in a field of pre-78 250 MX bikes at Canowindra last year... I suspect that for 90% of us, the tractability of such a bike would make it a brilliant choice (even though its down on peak power to the 250 MX bikes).