Worst of all when it was tightened into the cylinder head it pulled too far over towards the carburettor to allow the silencer box to be installed. After considering different fixes, I decided to just try bending it with a bit of heat. I got it clamped up with a vee block in the vice and was able to get enough heat into it with just a blowlamp to get it cherry red. Then a good pull made it move a bit. Of course it turned a bit bluey brown but I was able to polish that back out on the polishing mop.
It fits better now, so all's left is to re-weld the bracket lug on the silencer box into it's final position.