72 Dart 360 PVC valve issues

Not knowing a lot about how the motor was built, I won’t comment on the compression numbers. However, one bank being significantly lower than the other tells me it might be head gasket related. If the motor was just plain worn out, you would have low compression numbers, or more variance on all cylinders. It might be time to pull off the one head that has the low numbers and see if you can find evidence of a head gasket failure between six and eight. Posting pictures of the head gasket on here will allow us to see damage that you might not be seeing as obvious. This would also be a good time for you to examine the heads for evidence of oil being pulled in through the intake valve guide. This will show as oily buildup in the bowl area and on top of the valve. Bad rings don’t do this, only bad guides. You may get lucky and only need to do a valve job on your heads. Either way, I think that one head needs to come off at this point. On another note, have you seen any evidence of oil coming out between the block and the head? You said you saw oil smoke coming from underneath the car.