you want more timming at idle, so i'd connect it to full vacuum instead of ported.

i dont know what your build "should make" , vacuum wise. with the correct timing more than 9.

the vacuum advance goes away when you give it gas. it wont be the cause of pinging on normal throttling situations. the clowns that hammer it may have some problems...with their "brain".

your mechanical curve will be the culprit of causal throttle pinging.

700 rpms ? thats a big cam in there.