73 duster front tire suggestions needed

You can go narrower, but not much taller depending on the rim width. And skinnies are basically a preference, for looks, or low rolling resistance on a drag car. Frankly, not a great idea on a car that might need a panic stop on the street.
If the 235s don't rub anywhere, I'd keep em
(and 235s are only one size smaller than the biggest 14"tire easily available at this time. 14s are almost gone).