Reply to fried_guy,
The difference in opinion between rifraf and myself is not pertaining to the use of full or ported vacuum for the distributor.
Our difference of opinion is he is saying that as you open the throttle more and including full throttle the higher the vacuum will be at the ported vacuum port.
I am saying that at full throttle you will not have any vacuum at the ported vacuum port.
I have done a test where under a 35 mph cruise with gauges hooked up to the full and ported vacuum ports the full had a higher vacuum then the ported did.
The ported vacuum was so low at that point that the vacuum canister did not have enough vacuum to make any change in the advance at that cruise speed.