Thanks for the suggestions. I considered swapping to a 25 or 30 amp breaker, but decided it would only get me a little bit further with the test. There's no simple way to measure the torque required to keep the cam turning- at very slow speeds, such as turning it with a torque wrench, the cam "snaps" from one valve closing to the next opening. Yeah, a person could come up with a load-sensor on the motor mounting to get an average torque value at a decent speed, but that's more hassle than it's worth. I'm almost finished rigging the 7HP Kohler of my Wheelhorse to it- should have it going tomorrow. The Kohler power rating is at 3,400 RPM and I've got a pulley combination that will get the cam to 5,000 RPM- I'm confident the 7HP will do the job. "By accident" I discovered how to avoid most of the noise of the tractor running- the muffler had to be removed to clear the belt, so... now I'll cobble up a connection from the pipe stub to my exhaust hose and run the hose out of the garage!
With all the running I've done of the cam (with no faults) I've got enough confidence in the valvetrain, that I don't need to keep it visible by leaving the rocker cover off. I removed the temporary oil shields, cleaned up the oily mess, and installed the cover. Sure is much "nicer" to deal with now!