Ok, update,
This project could have gone a bit pear shaped.
After montmil pointed out the bike had an earlier engine than the chassis i asked a bike shop to check and they confirmed it ti be a '79 engine. OK
This weekend after checking through the carbs for some flooding i noticed the numbers weren't giving it as a 32mm . Upon further investigation on the interweb i find it's
an r45, oh no, will i still be allowed in the club.
Obviously a bit disappointed, but I've really taken to this bike. She runs sweet, sounds good and makes me grin.
Not knowing bm's well i had in my mind the engine and chassis no's don't match, this is apparently much later models. I checked the frame no. matched the documents so thought it was all good.
Way forward.... try to get a refund, probably not going to happen without mucho hassle, (Buyer beware).
Hang on to her as she is and have some slightly slower fun than anticipated and maybe put a r65 engine in if one comes along, (do the engines, gearbox, final drive match up on the various years 45/65's)? Plus side seems pretty frugal on the fuel.
Here's a picture of the latest incarnation..... everywhere i stop people comment on how great she is

Wadda ya all think?
Stu