The PS box is like 16:1 ratio vs I think 22:1 manual. So there's not a lot you can do. First would be to raise the front, back off the center adjuster on the steering box a little and make sure you can turn lock to lock without binding. Tighten up the adjuster till you get it just "snug" with the wheel centered. Test lock to lock, you don't want any binding. The PO may have cranked down on the adjuster to take play out of the steering. That only works a little bit and will tear up the box if overdone.
Also caster - those cars REALLY drive better with 2~2 1/2 degree caster added. Caster is what helps the car self-center when rolling. All our hotrods here have no less than 2 1/2. However, that may also increase steering effort, but should not a lot. It should still be useable - my wife's 70 Mustang racer has a 351C and a small Grant wheel. It was a PS car and still has the PS box. It takes some effort sitting or moving real slow, but once moving it's pretty easy to drive. She hasn't had any problem with it. Granted the front tires are MT Front runners 4 x 27.5"
Alternative is also "Flaming River".
Great looking ride!
