I have ran many older jeeps. People buy them without really ever knowing what they are getting into. Technology was totally different then than now.
A 57 would have came with a 4 banger and top speed was 40ish mph. A lot of them had engine swaps but the bigger engines added weight to the front end causing frame and suspension damage. You will have DRUM 9" brakes that will fade away after running threw water. Now us older guys learned to ride the brakes a little after water crossings to dry the brakes out!
The front end will be a D25/27 with closed knuckles. this has its own unique maintenance and issues. The rear will be a D44 offset with 2 peice axles. Upgrades are expensive! The transfercase will be a Spicer 18 and it will have a 3 speed trany.
The short Nose 5's are cool, but there is not a lot of room under the hood.
In offroad conditions! there are lots of little things like : clutch fading away, week brakes, under powered with large tires, small week axles with big tires, ect.
I have had a two 5's, two 2A's, two YJ's and a TJ plus a couple more. I have been down all those roads and conversions. Let the old stuff go to guys who whant to restore them. If you want a "wheeler"! build what ou have or one that has newer technology like a YJ.