I hope you don't have any problems, been there, done that. I have about 8 inches of vacuum at idle (built 400 Poncho). I had a drum booster on and it worked fine until the disc conversion and larger booster, then brick under the pedal time. I found through some white knuckle experience that the vacuum cans just don't work, maybe one meager stab at the brakes then whoa horse time, not to mention scary as hell.
There may be situations where you just need a little help the cans may work in but I have never found it personally. The vacuum won't get any better no matter what you do, low is low. The only easy fix IMO is an eighties GM auxiliary vacuum pump with the built in automatic regulator, on evilbay once in a while for around 100-150 bucks, otherwise rare as hens teeth. There is hydro-boost but that is another whole can of worms and a major project comparatively. The aftermarket pumps they sell at brake places and speed shops are more for drag cars I think, loud and shake the whole car no matter what you do, very expensive too. I had tried them all and was getting ready to pull my hair out, they just weren't right, lucky that Summit is close and will take almost anything back.
I researched more and found the GM pump was an easy solution to a big problem. They are automatic, small, very quiet, hardly draw any power, goes inline so you are still using some of your vacuum too. I put a vac gauge in just for the pump and it is always at between 17-22 inches, the needle jumps back up immediately after hitting the brakes, otherwise I would forget the pump is even there.
Just my two cents woof,
Allan