451Guy, to answer your question on the firewall reinforcement bracket when changing from a power brake unit to a manual brake master cylinder using the new style aluminum master, here are the pics of the one I modified:
A couple details that may be helpful to others.
1) You need the manual brake pushrod (as others stated)
2) I used a firewall reinforcement from a manual brake car, but you can drill the 4-bolt pattern into the power reinforcement. The car firewall has all the bolt patterns from the factory. You will also need to put the 1-5/8" diameter hole for the center of the master cylinder into the plate. It is lower than the power booster location. It actually intersects that old hole a little.
3) The brake lines will need to be bent a few inches to reach the new location.
4) I used 4 new 5/16 x 1.25" long bolts, to attach to the car. Self locking nuts are a good idea. I used the nuts that held the power brake booster on.
5) I readjusted the brake light switch, but it might have been fine as is. I moved it out of the way while I was working under the dash.
6) Throw away the power brake pivot linkage and short pushrod that connected to the pedal.
