what engine trans combo are you running? will you be upgrading to a power steering unit at some point as well? asking because the small diameter single diaphragm vacuum power brake units are not as effective for boost as a double diaphragm or larger diaphragm unit. due to limited space under the floor where the master cylinder is located some have gone to a hydroboost unit which uses a power steering pump as a hydraulic source. they work very well and there are kits available just like there are kits for a vacuum assist brake set up. the issue is you need a power steering pump to operate them.
when going to a disc/drum set up you may need to ask when buying the new master cylinder or kit. some master cylinders will be rebuilds and may have the built in residual valves in the outlet of the master cylinder. these were used for drum brakes to keep a residual pressure in the system so the lips of the seals in the wheel cylinders keep tight against the bores of the cylinders and didn't leak contaminants into the system or fluid out of the system as well as assist in keeping the wheel cylinder pistons from retracting all the way back, which helps with pedal travel. the disc brake set up can be a little different and some will use a 2 psi valve inline just to keep the pedal from getting spongy. with a low mount master cylinder you may require inline residual valves in order to get the system to work properly.
some info on brake valving
https://techtalk.mpbrakes.com/how-to...valve-overview
https://www.wilwood.com/search/partn...sidual%20valve
https://www.mico.com/sites/default/f...re%20Valve.PDF
https://www.speedwaymotors.com/shop/...RoCq08QAvD_BwE
an example of the hydroboost system
https://westernchassisinc.com/1955-5...ke-Assist-Kit/
some stuff to think about
https://itstillruns.com/single-dual-...r-6048376.html
https://techtalk.mpbrakes.com/booste...ur-classic-car
https://techtalk.mpbrakes.com/how-to...ng-pedal-ratio
https://techtalk.mpbrakes.com/componet-size
https://techtalk.mpbrakes.com/instal...-brake-booster
hope that didn't confuse you too much. better to be informed before spending cashola