Peavey sends me FREE schematics all the time. I'm sure they will be happy to assist you in this manner. The peavey website does have a pretty good forum on the repair and mods for there amps.
If you are right, and there is a 1ohm resistor, you would be measuring the voltage drop (mV) across it, not current. Example, 60mV reading = 60ma bias current. Using a 1ohm resistor makes this possibe. Internally should be a bias pot to raise or lower the negative bias voltage which in turn affects plate current.
The back of your amp may state how much voltage to read. If not call peavey to find out.