[55 Chevy Dave]

The 7" diameter brake booster would clearly not fit between the crossmember and the frame. I contacted Progressive Automotive to ask them if they had a solution. It turns out that they had an answer. I ordered their installation kit consisting of a recessed pan to be installed in the frame and a mounting plate for the master cylinder/brake booster that spans between the recessed pan in the frame and the crossmember.

I proceeded to cut out a portion of the frame and boxing plate to accept the new recessed pan and then test fit the master cylinder and booster.