[Jac Mac]

Mike
Due to the reverse pulse in the Individual Runner system of the IDA you wont have a constant signal on your ported vacuum as Bill D mentioned earlier, so to obtain it you have to bring all 8 to a common chamber prior to the dist, which all starts to get rather untidy.
I wonder if some of the later MSD such as the Digital 7 could be used in the following manner; These have a timing retard for each gear of 5°-- Now you should be able to have that hooked up in your situation so that you run in cruise mode with the extra advance dialed in, but when you stand on the gas to accelerate it retards by 5° to prevent any problems- sort of back to front to its original purpose but would suit your application. These retards etc are operated by solenoids & micro switches fitted to the throttle linkage/gearshift etc.
The Power Brake booster will function with a feed from only one runner, but an additional vacuum tank would help if you plan on descending any long mountainous roads requiring frequent brake usage etc.
The pic of the valley mounted system is the best if you need to operate the vac controlled systems etc of the AC.

Jac Mac