Yes, my guess is that is a very early K200A amp with a single sided preamp power supply. I will assume that there is no negative power supply going to the preamp boards?
Normally, when an output goes bad in these amps, they will blow fuses and take out other components as well. If the outputs don't test as shorted, I would look at the rest of the power amp circuit.
Check for burned or open resistors, shorted caps, shorted transistors, etc.
If your meter has a diode test setting, use that to test the transistors, if not use a low ohm setting. 4 meg and 700K readings don't mean much here as the meter may not be applying enough voltage to forward bias the junctions.
Be sure not to connect the speaker to the amp until you have the voltage on the output fixed. You don't need to ruin the speaker while you are working on the head.