Engagement should be at peak torque for your engine.
Consult your engine builder for this information.
We build/rebuild clutches for hundreds of racers. From the customers and their engine builders' information, anywhere between 3600 - 4200 for a big pipe AKRA clone.
If you have it set up where you suggest, you'll be in the ballpark. 1 bolt/nut in the outside of each weight lever, red springs @ .235" will get you around 3800 rpm.
Yes you can with red springs set at .210 will get you at 3600 rpm if you want any higher engagement take the inside bolt out of the levers and start around .235 to .240 on the spring setting