On my 216's I try to keep it below 3500 rpm. there are websites where you can enter your final drive ratio, wheel diameter, and speed to calculate rpm. Your 46 stylemaster is probably close to my 1/2 ton, 3 speed column, 216 engine. 16x6 tires.
resto pack The resto pack for a 46 sedan shows the standard rear end as a 4.11 and there is an optional 3.73,
The resto pack also shows the power curve for the 216 engine. It drops off at 3500rpms for horsepower, and torque drops off at 1900 rpms
So I put in 28" for the tire height, 1.00 for the top gear in the trans, 4.11 for the final drive, and 65mph for the speed. this gave me a rpm of 3206.
65 is pretty fast for these old vehicles, mainly for the brake system.
I generally cruise at 50 in my trucks, and push it over a little bit every other drive to clear out the cylinders. also remember if you are runing the stock fan is noisy.
Hope that helps.