Turf 8hp Kawasaki primary clutch question

I am trying to set the unit up so that it doesn't stop the engine every time I need to jump off for a second.
I have bypassed all the switches that ground the coil to shut it off and it still has a tendency to want to creep ahead at a 600 rpm idle.

Being very familiar with snowmobile clutching I can see the clutch relaxes another 1/4" further as the engine shuts off than at at idle.
If this were a snowmobile clutch it would tell me that the primary clutch spring, clutch bushings are weak/worn and not pulling the sheaves back all the way at spec idle.
I might increase the clutch distances slightly to help, but would also like it running as designed.
The poor old thing has 4400 hours on it and the spring must be real tired.

I see in the manual that it should idle around 700 rpm and the primary clutch should engage at around 1100 rpm.

I have dozens of clutch pullers for snowmobiles and was wondering if anyone would know the length and thread of the puller that I would need to pull this clutch?
Also, should I expect the clutch to pull all the way back at a 600 rpm idle?

Lastly, can a person buy a slightly heavier spring for this clutch so that I can use as I would like?

Appreciate any thought's