Harmonic balancer question

[Nixon1]

I'm asking this for a friend..

He's got a 65 Mustang that he just dropped a 302 he rebuilt in. It's got all new internals, cast though, and a low rpm torque cam.....it's actually a cam meant for RVs. He's in his break-in period right now and has barely driven the car over 100 miles. His harmonic balancer is shot. It gives him a timing reading of 40 degrees advanced for the car to run AT ALL, and as soon as he hits around 1800-2000 rpms the engine starts to vibrate very roughly. He rarely takes it over 2000 rpms. How long can he go like this before damaging his bearings, etc? I'm sure he plans on another few weeks of driving before replacing it. The engine is cabureted also.

Also....the heads he put on are warped so the car can't go very far, maybe 15 miles, before it starts to overheat and blow coolant past his head gasket. One of his spark plugs is covered in oil.

He's too stubborn to park the car or do anything to fix it right now...how badly can he be damaging his engine? I think it's toast, but he's sure it's just perfectly fine and that nothing bad is going to happen, he just needs to fix these things.