Roy,
The distributor moving, suddenly out of time, can cause loss of power, but reduced compression across the board points to valve timing, not solely ignition timing.
Say the cam timing changed, then so did the ignition timing.
If you then only correct ignition timing to gain some power back you've ignored the possible source of the problem, something within the timing gears. If valve timing is off much it still won't run as nice as it did before even if ignition timing is best it can be given the situation.
