I have too many projects lined up so might be willing to part with this frame. It is from a blue TTR250 that has never been registered in the UK.
There were a couple of complete TTRs on eBay going for a song because they can't be registered for road use - see here and here
My frame plus a TTR such as those would make a great project and a very cheap road legal TTR250.
The registration process is:
build the bike up in the new frame,
contact Yamaha who will provide you with a dating certificate for £40ish,
using the frame number on the frame, MOT the "new" bike,
and insure the TTR on the frame number.
This is now a pucca bike from a DVLA perspective and they will provide an age-related registration number, tax the TTR accordingly and off you go.
NB What you must do, within a month, is give the new registration number to the insurance company, and they will re-issue the insurance certificate with this new number.
There were a couple of small cracks (quite common on trail ridden TTRs) where the subframe joins the main engine/suspension cradle and I have had them professionally welded up.
I would get the frame shot blasted and powder coated to give the metallic blue finish that is very close to the original - or as close as you can get with powder coating!
The finished frame, ready to accept your donor parts, would be £220 including carriage within the UK.
I have just spoken to Yamaha UK and the frame is from a genuine UK specification "TT250R" manufactured in 2003. They confirmed that the official "dating certificate" letter costs £40.
It is currently with the powder coaters and expected to be ready for collection any day now.