If the 450 s/a would fit, ( length,shock mounts,and match-up with the frame and bearings ) I would try that rather than cut & weld a stock one. Your top shock mount on the frame left side would need to be modded also.
If you try to mod the stocker you will need a GOOD welder.
If the 450 s/a works, post it. It would be nice to try with a narrower belt to get rid of the left side bulge.
Just looked at a picture, it looks shorter, and mounts inside the frame not outside.
Post a pic of the two side by side.

I wouldn't risk cutting and welding on the swingarm. Alignment is critical so you would need some kind of a jig to keep it straight while welding. It doesn't take much misalignment to make it handle funny in a turn. And if you do manage to keep everything straight, you are still betting your life that those welds aren't going to break while you are riding it. Chromoly gets brittle from the heat of welding if not done correctly. Guess what these frames are made from.

mild steel.

I forget that you guys haven't modified your bikes to the extent that I have. Mine does have moly. The advantages of working in a shop that fabricates frames and suspensions for race cars.  

I didn't like the offset left shock. Narrowed the pulley and belt. Modified the top frame mount (didn't have to weld anything). Made a new lower shock mount for the aftermarket shock. Now it's almost symmetrical.

SpamyToo wrote on 07/17/21 at 18:00:44:


The same way that you build a full chassis for a '67 Camaro, like this.

I don't work in that department anymore, and I am retiring in a few weeks so you would be at the mercy of whatever those guys would charge for that. I'm sure that they could do it but I am also sure that it wouldn't be cheap.