Thanks for your replies, I'll try to get it down to motoliner tomorrow, he had a quick look at the blue frame & quickly condemned it for £nowt. Think it's £50 for an alignment check, at least the swing arm spindle goes through ok on the black frame, you'd need a 5lb hammer to forge the spindle through the other frame
Welder responsible for the blue frame efforts got no suckysucky, doesn't deserve to ever have any either, very poor effort
matt those welds on the black frame where never added in suzuki land, looks like somebody removed rear frame work including lower rear loops, but then decided against it and welded the whole lot back on, and unfortunately the blue frame is just scrap because centre spine should be straight, but unless my eyes deceive me the 2 outer top rails are bent in the last 3" also, so i would think its either been flipped backwards or rear ended by another vehicle. If you're having black frame moto-linear checked then hopefully it's all Ok.
Also forgot to ask is there any similar weld marks along the seat rails ??
matt not sure if i'd bother getting black frame checked on linear jig, having studied your pictures yes can confirm the back end has been cut in the 6 places indicated.
But as best can inspect you pictures of headstock area all still looks 100% original weld, and putting frame on a jig will only confirm that rear shock top mounting point is in a different location to stock, which if you are going monoshock route will not make a difference, as for straightness of seat rails you can check most of that by using string along center line from headstock going back to tail area.
Nearly forgot i would not bother checking against blue frame as that's definitely a no no for dimension references, and regards blue frame if you did pay by paypal get in-touch with them and explain situation and as long as there's not a long time since purchase think you'll find they will rule in your favour, and do not send it back as it's only fit for scrap and not worth the return cost unless seller covers that !!
On the black frame you could fit bodywork if you have some and see what the fit looks like.
If the back of the back one has been raised as we think & presuming stock length shocks were used that would lower the rear either that or someone has used longer shocks & altered the frame to keep the stock height, none of which matters if you are going monoshock with it
Where there may be an issue is with fitting stock seat, side panels etc
Don't take too much notice if the seat rails & shock mounts look slightly off on either frame they all look like that sir
Has the inside of the swingarm pivot point been ground away to fit a different arm ?
If it were me I would be tempted to fit stock running gear & check wheel alignment as that's what really matters .... easy for me as I have a mate with a shed full of stock wheels etc but I realise it could be a problem if you don't have access to stock stuff