How to improve a 4700's horrible ride?

(It's only got six wheels, but I figure this would be the best place to get advice. Please advise if there's a better place to ask)

Howdy, yall! I just picked up a 98 International 4700 with a DT466E and Spicer 5-speed. It's not my first medium-duty, but it is by a vast margin the most gawdawful misery box I've ever had the displeasure of riding in. I don't understand how I can roll over a curb and hardly notice, but on smooth pavement it lurches and bucks like a demented carnival ride. Up and down would just be a firm suspension, but why is it shaking me back and forth? My first thought was engine/driveline stumbling, but clutch in and there's no change. Runs great and seems like for the 2500 mile move I bought it for, it'll survive, I'm just not sure I will.

The bench seat isn't off to a great start, but there's something wrong with a front suspension that's so ill-mannered it makes me wish I were in a farm tractor. Solid axles are nothing new to me; my 1981 Toyota 4x4 has been a semi-daily driver for 13 years and counting, and I can drive it for 12+ hours without issue. This International is downright abusive; one four-hour drive and I need two days to recover and start to get a panic attack just thinking about driving it again. Apart from a better seat, what can I do to make it more bearable? I'm sure the front shocks are original; what are good replacements? I'm a mechanic (mostly lighter stuff) and not afraid of some fab work, just looking for others' experiences with this chassis.