Correct PTO RPM for bush hogging?

[Tractorable]

On my 8N, PTO speed is "just below to top bolt" on the throttle, haha. I have no idea cause my proofmeter is busted. I just go by ear....when it bogs down I goose it then back off when things are lighter.

There's a nice 1972 Ford 3000 for sale two miles down the road from me, hmmmm