yes Pokey - you're right. probably a lot of drama trying to register a dirt bike that hasn't been registered before. And maybe more prudent to get hold of a similar year TS frame and swap all the motocross bits onto it. I have been looking for some time for a 74-75 TS donor, but haven't seen anything worthy yet.
My other and more preferred option now after thinking about it is to VMX it in pre75, but it doesn't comply due to the amount of rear end suspension travel being greater than 4". So I need a 74 frame and swing arm to then swap the rest of the bikes running gear onto that. Likewise these 74 frames/swing arms in straight or unmolested nick seem to be rare as rocking horse poo and i can't seem to find one. (would welcome any leads).
I made a hasty purchase on eBay a few years ago and ended up with a 75 TM250M not knowing about the VMX year catageories at the time, and realise now I should really have got a 74 250L model. Lesson learnt. I don't mind that much tho as it is all original as it came from off the factory and unrestored, with low hours.
Cheers for the advise guys