I might run mine at about 18 pounds or so. It's progressing nicely, hope to have everything back together in the next week or ten days.
You're right about the tire pressures...I had a very cool old Lincoln Mark IV, and every time I had the oil changed they pumped the tires up to 35 pounds, and the car rode like it had bricks for shocks. Dropping the tire pressures down to 19 pounds or so, as specified by the factory, made it ride like a magic carpet ride again.
It is not recommended to use high pressures like 30 PSI (considering original tire sizes) because it can accelerate damages on the fiberglass body.
The pressure that is suggested on the owner's manual is 16 for front tires and 18 for rear tires. You can also use 19 in front and 22 in the back to get a road if your intention is to achieve higher speeds.