Ed,
When I recommended the 100pF caps, I was thinking of the Series ll version. However, you are right, the Series l should use a smaller cap on the pre-driver base to collector predriver transistors.
The PL service bulletins were filled with good information, however, one item I find interesting, that was never published from PL, was the addition of output stage base stopper resistors. This was well known at the time to reduce output stage oscillations. This revision alone can stop oscillations, especially with the long lead wires from the driver board to the hand-wired output stage. This should have been included in the PL production design.
VSAT88,
I understand your dilemma. I would get the 700 running back to original, then add the 2.7 Ohm base stopper resistors for good measure. These will not cause oscillations (not supposed to), but it more than likely will suppress the urge for the map to go wild anytime in the future with various loads and output levels. Almost all paralleled output stage designs nowadays use base stopper resistors, especially in a triple emitter follower (EF3) configuration.
Also, if your amp does not have film bypass caps such as the 0.33uF / 100V caps as in my attached schematic, you may want to add those too.