It's quite likely a 232. They were the only I6 that DJ's came with. The tranny is probably an AMC modified torqueflight 949 .
You absolutely WILL have to change the spring perches. The DJ-5 has leaf springs that are "outboarded" on pins to make it more stable on the road. Most of your CJ suspension parts aren't going to transfer directly.
I would highly recommend disc brakes and an updated braking system. The stock brakes are 4 wheel drums and the master clinder is directly levered to the pedal and has terrible leverage. Stopping those tires with stock brakes would be a good workout
I haven't converted mine yet, but since I bought a JK, the DJ has acquired "toy" status and it's just a matter of time, but I've been toying with it for 10 years and it's a heckuva lot of fun
There are probably too many small difference to just list them out, but if you have specific questions, I can probably answer a good portion of em.
As far as being worth it? I paid $400 for mine, and I've spent another thousand or two on materials and toys to mod it with ($300 just for aluminum diamond plate... body armor, dash, etc.), and it is well worth every penny
If I park it next to a $100k mega built JK project, twice as many people will look at mine, and 10 times as many people will ask me about it. It's one of those vehicles that is just fun as **** and attracts attention.
almost EVERY single jeep on the road will wave at it
And a few answers to the common questions to get you started-
"where did you get it?"
I set up an ambush at the mailbox and carjacked the mailman.
"is it hard to drive on the right side?"
I don't know, is it hard to drive on the wrong
"is that legal?"
No, I have to buy plates and inspection stickers on the black market and all mailmen have to be criminals to get hired.