Hi Dave....Both my 56 Bubbles had Hydraulic brakes. They made wonderful scrap junk. I think you will find it better, by far, and cheaper, by far, to just upgrade to modern electric brakes and hubs. How 'bout pictures of the Bubble. We have to stick together.
"If it can't be reduced, reused, repaired, rebuilt, refurbished, refinished, resold, recycled or composted
then it should be restricted, redesigned or removed from production."