Is my Vacuum too low?

Fuel-level is , maybe not critical exactly, for the most part, but at idle it kindof is. This circuit is exceptionally sensitive, and the whole deal was designed to run at a certain WET fuel level. So you can get the other circuits to run pretty good even with a wrong level, but if it ain't real close at idle, you will have problems. And if it ain't stable, then you'll have even more problems.
I've never seen a WET fuel level for a carb like yours. The instructions in the kit,spec an upside down float height, that with the factory spec fuel-pressure, is supposed to get to the design WET level.
Jus saying.
If the WET fuel level is too high at idle, and assuming your T-slot sync is right,the engine will have an easy time of pulling the fuel up the idlewell and thru the discharge ports; maybe too easy, and the lowspeed circuit goes rich and there's nothing you can do about it.
Conversely, if the WET fuel level is too low, the engine may have a hard time pulling the fuel over, she goes lean, and the trimmers are all the way out, and you still have a rough stinky idle.
Jus saying.
These are your clues,after the T-slot sync is set, and if the trimmers won't come in at 2 turns +/- .5turn.
If you want to see how sensitive your particular carb is; just pinch the fuel supply line shut, while the engine is idling. One of three things is gonna happen;
1) the engine will continue to idle at the same rpm for a while,like maybe up to a minute, then slow down, idle rough, and finally stall, as pick-up becomes too difficult. This is normal
2) the engine will gain rpm as it stops being pig-rich, then continue as #1
3) the engine will almost immediately slow down, run rough, and stall, cuz it just can't pull up the fuel.
4) and a bazzillion degrees of in-betweens.
With every thing set right and synced up and a healthy warm engine, you should be able to reach in twist the key and almost as fast as it's done the engine is running. click-Vroom. I tell you that warms my heart every time it happens. And it always always reminds me of the little 260s in the early Falcons; click-Vroom. and maybe the 68 302s also; click-vroom. Install a mini-starter and BadaBoom, you never again have to listen to the patented Mopar; I think I can,I think I can,I think I can..

We had -39C and change in my town last weekend; BEFORE windchill lol. For our American friends;
-40C = -40F; awful daymn cold. And we won't even mention the humidity.