There is no rule that a brake booster/master cylinder has to be mounted in or near the factory location. We have mounted them several feet rearward and used a larger diameter actuator rod (tubing) with a short 3/8 rod at the pedal and booster. On a 31 Plymouth taxi the frame was so narrow there was no room till just in front of the rear axle so we used a bellcrank at the pedal end to convert the rod to a puller and a second bellcrank at the booster to convert back to a pusher. If you google "remote mount brake booster" it shows ones that can be mounted in the trunk or anywhere you have room. IIRC a 57 T-bird with power brakes had the booster by the radiator. The factory mounted master cylinder had a line run to a slave cylinder on the booster that pushed the rod into the booster when you stepped on the brake.
