A500 rebuild. Removing lockup?

Safe bet is to keep your stall 3-400 below your highway cruising rpm. You’ll need to play with calculators to find that magic number with your gearing.
You can get closer than 3-400...
but risk boiling due to not coupling often enough to keep fluid cool.
I’ll add this too for thought:
For a “pro touring” type of set up, a coupling speed 200 rpm uunder where your cam comes in makes for a very responsive car.