The "hot air" integral chokes did use a small vacuum pull to help pull the warmer air into the choke coil housing, but I'm not sure that would be needed on a full-electric integral choke set-up. If there's an open hole, for now, find some way to reliably plug it. I'm not sure if that's the reason for the performance/adjustment issues you're having, though. The vacuum "leak" you mention would be what it is, but shouldn't really be that "big" compared to something like a broken vacuum line or something like that.
When driving a car with a "highway" rear axle ratio, going from idle to WOT doesn't seem to work as well in getting things moving as a part-throttle punch and then to WOT after the engine has enough rpm to really need the secondaries in low gear. Best to aim for sharp off-idle response with the correct hot base idle speed.
By observation, it's good to want to rely upon what the prior owner told you about the car, but doing your own investigation/research to confirm what you've been told, up front, usually works best. Just my respective observation. AND that can also go for what any tech hotline operative might tell you, too.
To me, without further investigation on my part, the electric choke is an add-on for the basic carb design. Just as some AFBs had integral chokes and some had divorced chokes on the OEM carbs back then. Didn't change the basic guts of the carb, just what was on the outside related to what modulated the choke on the carb. There were aftermarket choke cable kits to make an "automatic" choke into a "manual" choke, back then.
Many people who grew up with manual chokes seem to consider an automatic choke "troublesome" as they aged, so they put in the manual choke cable to suit their desires/needs. Personally, it might take a little bit to finesse an automatic choke to best fit the particular application, but once I get to that point, where I'm satisfied, that's all that's needed for a long time. Even if the particular carb is a "factory replacement" OEM-spec carb.
Keep us posted on your progress.
CBODY67