The vacuum brake booster will not fit with the LS1 tucked back in as far as it is. I didn’
t want manual brakes so I went hunting for other options. What I found is that
several BMWs used a hydraulic booster that is very compact and should be able to
package in the space I have. This booster is powered by the power steering instead
of engine vacuum. Versions of this booster were used on 1988 and earlier 735s, all
750s, all 850s, and I believe some 5 series but I’m not sure what years. I found one
from a 1991 750i at a local bone yard. The 750 setup consist of an accumulator, a
regulator, booster and master cylinder.
This link shows the operation and plumbing
setup. If you use a 735 set up the pressure regulator is built into the accumulator. I
paid $400 for everything including the plumbing. New the stuff would be close to
$2,000 even in discount stores!

Another option is to use a booster and MC from a 4.6L Mustang. They used the Bosch
hydroboost system for a number of years. The accumulator is integral to the booster
and makes for a simplified package. The downside is it is a heavier package than the
750i. These system are easily found on Ebay for under $100. I am going to see if one
will fit as this is an easier and cheaper way to go. If it works I will resell the BMW

Well the Mustang hydroboost works perfect! I had to modify the pedal to accept the
eyelet style pushrod and make a new flat mounting plate but it fits in beautifully! Now
I just have to make up the power steering lines and it should be ready to roll.