I think all the US Kats were 1000cc. Not positive but pretty sure.
I've got a 1979 2V GS1000S as well, , not as much fun as the Kat, they are much rarer than the Kat though.
I made an adapter to fit my engine to the same type of engine stand.
Did not add any support to front end as you did, still worked fine .
Engine was on there all winter no problem.
I did the same thing a while back HUGE difference.
If you want to get rid of the anti dive completely these are very good.
https://tractechmfg.com/product/gs1000-gs1100-anti-dive-by-pass-plates/