Since the 235 engines only have one vacuum port you are really limited on options. You should be able to use a 'T' fitting and operate both. I had the disc brake/booster combination on my 56 along with a PCV before I converted to a V-8. It worked fine.
Fred


1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine