So, the cam was seized in the bolt-on collar on the front of the head. I pulled it off, took it back to the machine shop, where it was re-honed and liberally lubed before installation. Got it back on and started the car. Drove it about 10 miles before it seized again. Not in the collar this time, but somewhere in the head itself. I can turn it very slowly, but something is jammed up. So back it goes. Wondering if I need a new cam altogether?
It also ripped the cogged roller out of the water pump and chewed the timing belt. Good times.