Lots of guys have done Dakota frame swaps, some with a lot of experience on newer stuff (after 96) then I have.

In answer to your question. I think a 93 Dakota chassis will work well under a 55 Dodge 1/2 ton pickup. The width of the Dakota front and rear suspension (the rear suspension is good, but a Dakota rear axle is going to be 4" more narrow then your 55. You may have to put a mini tub in the box sides to clear a Dakota rear axle) is probably about the closest to the width of your 55 Dodge of any modern chassis. You may have to use the Dakota wheels on the front, but a lot of that will depend on the look you like, rather then a requirement for tire clearance. I will warn you that the lower you want the truck to sit, the more of an issue front tire clearance becomes. At normal ride height, I don't foresee any problems.

You are probably going to have to shorten the wheel base (the distance between the front axle and the rear axle), I doubt the Dakota donor you have will have the correct wheel base. A standard cab, short box Dakota will probably be too short of a wheel base, it is much easier to shorten the wheel base then it is to make it longer. A standard cab, long box Dakota is probably 7" -8" too long. Its pretty easy to remove 7" - 8" right behind where the back of the cab ends. An extended cab short box it probably around 18" too long. Gene