There r plenty of mid 90s XL and XLV liberty's with straight axles and they also used cruisair and the roofs have very little on them. Rocky has one. If u can go back to ride height once u r inside, front suspension type would not be a concern.
Straight axles ride just as good, possibly softer when compared to a IFS front end with 365s with 18000lbs or more on it. They r also less complicated and less costly to keep. I do not view a straight axle as a detriment. In a lot of ways it's a plus but not a deal breaker either way unless u have to keep suspension dumped over long periods I do not suggest that.
That vintage could also be a jake brake instead of the trans retarder.
Nothing sounds like a 3406 gettin goin, pulling a hill at 5mph with 80000lb at 900 rpm with little to no throttle. Gettin er all the way up and thru 7th gear direct range, barley seeing 1200rpm along the way. It's cerebral. Cats growl just like they should.
Buses, they just sound like buses. Sosorry