Could be you need a different height seat pedestal rather than seat. Do you feel you are too far from the pedals or the wheel?
In 1974 the batteries were still mounted in the front behind the front access panel, and so you would have no restriction on changing pedestal and so height (from 1977 on the batteries moved to a box that sits under the seat and restricts that option).
I use the highest pedestal I could buy (10") plus a 3" extension, with the seat back as far as it can go and I am only 5' 9" and most folks have the opposite issue (can't get far enough back from the pedals, or in my case wheel (I am nearly as round as I am high!)), so you have a lot of scope to move closer.