If you wanted to update the brake system, but still have a Hydrovac, then take a look at the catalogs at NAPA.
They offer (original for other model vehicles) newer style Hydrovacs.
You may want to swap to a dual circuit master cylinder, and use dual Hydrovac, this was standard practice on a number of vehicles.
A cheaper simpler solution would be a dual circuit master cylinder with attached booster, still mounted under the floor.
Grigg
