[yossarian19]

There's a guy on here, SCHRUM or some such username, who was / is putting a '57 onto a GMT-400 (88-98) frame.
I've seen a 4x4 GMT 400 / 1956 truck locally and the 4x4 axles are a tad wide (or this guy's back spacing wasn't enough) but it does work and looks good. He was very happy with how it drove.

Adapting any parts from the '98 chassis to the '57 frame is going to be an uphill fight all the way. I wouldn't bother. Easier to chop the '98 frame, adjust length as needed, re-weld, fish plate & make body mounts (I think) than to try and graft a 98 frame section in, or fabricate suspension mounts correctly.