Putting 17" or larger wheels will change the comfort level, no sidewall. My '69 with tubular front, triangulated 4-link rear and 15" wheels rides the best.
There is more to ride quality than sidewall. A cheap set of shocks with bigger TB's can make a car ride like an empty dump truck, for example.
I like the ride of my '74 with 245/45R17's, .99 TB's and RCD's. Certainly no worse than the '15 Challenger R/T STP I used to own. Even drove them back to back and other than the slow 24:1 manual box the Duster had at the time they seemed to ride and handle about the same. Purely subjective, but that's my opinion.