[Coupeguy2001]

Hey Denee,
I put a saginaw box in my 57, and the steering is way too light. After pushing and pulling the original steering for over 40 years, it takes a lot of getting used to.
I went to a steering box rebuilder, and talked with them about the steering, and they told me that the late 60's and 70's cars were set up for one finger steering.
What they do is change the torque bar inside the box to give it some road feel. With everything I have done to my truck, the steering was the biggest disappointment.
I haven't got my box modified yet only because I have to change the lower most u joint, pay to have the box modified, and the truck will be apart again and I can't drive it.

As far as the brakes, I too put a proportioning valve in my truck, and turned it way down to the lowest point. The truck stopped ok, but I have a hydroboost, and it should have stopped faster. When i turned up the proportioning valve, the rear brakes were starting to work. Then I readjusted them some more after the fuzz wore off the linings, and it stops really good now.

Exhaust:
Why don't you measure the output of the header collector couplings, and go to the muffler shop that is going to do your work and get them to give you two 4 foot pieces of tube, and tack them on so you can get the noise back farther while you do your troubleshooting? They are going to get the tubes back anyway.

Temp:
your condenser covers up most of the radiator opening. Your condenser might be too large for the opening. You really want more airflow over the radiator that isn't already heated by the condenser. You might want to try putting some spacers on the condenser so it is forward a little more and get some air to go around it instead of through it. Go out and look at your Mazda, and determine how much percentage of radiator is unobstructed by the condenser, and try to get that amount for your truck.
Otherwise, What thermostat are you running? If the thermostat is 180, it will not let the water temp go below 180. and slows down your cooling when the engine might be happy with a 160 thermostat.
Also, you might drill two 1/8" holes in the perimeter of the thermostat to eliminate any trapped air that might get caught in that void on the outer ring of the thermostat.
It has been my experience with my truck that the water will seek it's own level unless you have a cap that draws the water back into the radiator when cold. If you have an original style cap, the water will keep burping into the catch tank, and the cap never lets the water go back into the radiator.
If there is no catch tank, the water will just keep burping.
You can still buy 7 pound caps that will work with a catch tank. If you have a later style radiator, you can go to a 15 pound cap and a catch tank. I would find out from whoever made your radiator what the recommended pressure cap is for that radiator.