I agree with 68gmsee; though you might love your buckets, go borrow
a full foam bench seat from a 67-68. That would be your most affordable
way to begin diagnosing the ridability problems.
If you are happy with the difference, begin shopping for buckets
from a high-end SUV.
Short sidewalls do make for a harsh ride. I think you will find that you
have to sacrifice some ride quality for looks.
The bigger wheel/ smaller tires look grand but the more cush between you
and the road, the better, if looking for nice ride.
Furthermore, all tires are not equal...given the same size, some are made
for performance, some for comfort.
Perhaps look into tires designed for a large, luxury SUV or sedan.
My 2 cents
