'75 CJ Drive Train Upgrades?

I have a 1975 CJ-5 that has 36,000 actual 1-owner miles (I bought it new). It's been playing "Sleeping Beauty" under an Elm in my back yard since about '01. I am thinking about swapping out the transmission and transfer case (or the entire drive train) for something later vintage. I would like to stay with a 258 cuin type block, but have an automatic tranny, and modern transfer case (preferably selectable for 2 or 4 WD). I can keep the stock axles, they have automatic hubs, and 3.73 gears.
I’m also interested in an OBDII unit with fuel injection for reliability. so a engine swap would come along with the project. Currently, I have a 258 with a Holley 750, big valves, and a .500 lift cam & Headers, that’s a little too ‘torkey’ for the street, but I want to be able to switch back to the current set up if I decide to. This car is a ‘survivor’, never been repainted, only mods were as listed above and I installed a GMC truck type 4 speed to stop tearing input
shafts in two when accelerating (went through 3 trannys in one summer that way) they were driven by an 11” clutch /pressure plate from a 1ton GMC wrecker. Oh yes, it has Mopar High back bucket seats, roll cage, & 5 point harnesses for when I was racing it.
What ‘donor’ vehicle would you recommend I search for to make this a bolt-in swap? I figure I will have to get new driveshafts built, so that’s not a problem. I’m thinking Liberty, Patriot, Cherokee, or Wagoneer, year & type ???

I’m turning 68 in January, and have had a broken back, and hip replacement; but I still want my old CJ to putt around in (now that it is an antique) in my retirement years. It COULD become a daily driver if I can get it working to suit me.