First off, welcome
Next, there are many choices for your '51. Many dependent on your skills, time, money, and ultimate end goal. Restoration vs Resto-Mod vs Resto-Rod vs Rat Rod vs..... Stock ride height, lowered a little, lowered a little more, slammed.
Below are some examples of frame swap and/or suspension:
Using the S-10 frame with 2" front wheel spacers in front and an S-10 4x4 axle out back (S-10's have a 54.5" track width, your 51 is closer to 58") From there, there are two choices
1.) Using the AD kit
2.) Using your own fabrication skills
Using a GM metric frame (El Camino, Malibu, etc. All have 58" wheel base) I have only seen one AD on an El Camino Frame
Use existing frame and add IFS (no particular order)
1.) Weld in or Bolt in Mustang 2
2.) Bolt in AMC Pacer
3.) Bolt in Narrowed later model GM truck suspension
4.) Weld in or Bolt in GM metric front suspension (more on that later)
5.) C4 Corvette suspension
Make your own frame, add whatever suspension you want
It was once
stated , "There are two kinds of people, those who weld, and those who dont"
