$135 for a Hydrovac or a
vac booster? Just askin coz there's a big difference between the 70's & 50's bolts. The cheapest I could find a new Bendix Hydrovac for my '56 was pushin $400.
If one isn't real particular about keeping it stock, I have seen a couple aftermarket brake systems that use
dual m/c & saw one kit that used two small booster cans that could be adapted to our older bolts (cant seem to find that link, sorry).
Or, there's this
frame mounted hydrobooster kit for $500