What happens if you jack up both wheels clear of the ground and start it? Does the steering wheel stay put or does it wander off by itself?

If you are say making a left or right turn at an intersection and just let go of the wheel, will it come back to center on its own? With that much caster it should fly back. Stock spec is like 1 deg. If it won't come back, I'd check for a seized balljoint or joints.

1/8 toe is supposed to be the max for radials if that's what it's running. Bias calls for up to 1/4".

Those have a trailing arm coil suspension, yes? Grasping here but make sure none of the bushings are worn out. They don't drive nice if they steer from both ends.

Nice car by the way. Had a chance to buy a 58 348 tripower like that in triple black complete with continental almost 30 years ago. Everything original except the diamond tuck interior and the TH350. Prepped and ready for paint with enough NOS trim to do the entire car with at least another complete set for spares. $5000.

Passed in favor of a 59 Edsel wagon...

Kevin