I know the '71-3's are not that well represented here... but there appears to be a lot of overall Mustang knowledge so I will give this a shot:
As seen in the attached photo, my '71 429 "J" Code convertible appears to have come with an electric ported vacuum switch vs. the more prevalent ported vacuum switch found on most of these cars that had the BB engine installed. Unfortunately, the wiring and hookups were long gone by the time I got the car. I am at the point on my restoration where I am trying to restore this EPVS on my original engine. I have tracked down the correct wiring/connector as shown in another picture below, but I am now trying to determine the correct electrical connection procedure for the top side of this engine as it relates to this switch.
I should note that the car did come with the Rochester carb c/w the electric solenoid (anti-dieseling). The original firewall harness does have the white bullet connection which as I understand it, was used for emissions type connections as it only receives power when the ignition is on. This would also coincide with the carb electric solenoid as it would only be activated with the ignition turned on. In absence of true electrical schematics covering this topic, I believe this same principal can be applied to the EVPS as well (for the time being). You will note that the EVPS wire connector (rectangle at the valve cover in the photo) also has an additional bullet type connector (at the valve cover in the photo), which at this time I believe is used to connect to the carb solenoid. In this manner, these two electric devices would then terminate together at the white bullet connection mentioned above.
Does anyone know if there is anything in writing out there from the factory relating to the correct hook up of these two devices on my engine and does anyone have a reasonable assumption as to why some cars got the EPVS vs the more widely used PVS? I understand the reason has to do with the fact that the car came with A/C, but have not seen this confirmed one way or another. I have researched numerous Ford publications and I cannot find any detailed information on the electrical wiring aspect of the EVPS on the '71 Mustang and these publications all refer to the EPVS install solely on the basis of "depending on the engine installed" scenario. It appears the factory had many applications available depending on the car, engine, accessories, and possibly final location of the car for initial delivery. Helpful thoughts appreciated!