IDK where you got that information, but it lists the engine as being V-shaped, which it's not. If you run your VIN thru a better website, it will show you much better information, plus all the options it was built with as well as paint color and trim.

Before you jump into this with no parachute, the engine should be investigated to see what is actually wrong with it. There are many tests the can be done to determine that and could save you the major cost of replacement that may not be necessary. Oil leaks are no big deal, however smoking from the tailpipe could mean bad compression and burning oil. Drain some oil from the pan for a sample and let it sit for awhile to see if there is coolant in it. A Mason jar is a good container so you can see if it separates out.

Also check the rest of the drivetrain, transmission, transfer case, and differentials as well as body condition underneath before you go investing around $2000 bucks into a 20 year-old vehicle. I'm not saying there IS something wrong with it, but it would give you an idea if it's worth spending the money on it. If money is no object, go for it! In my opinion, there is not much point in NOT making sure the cylinder head is replaced if it's cracked or has a blown head gasket since that 0331 head will always be around to bite you later. There are currently 2 options for replacement cylinder heads. The 2002 and later model "TUPY" head made by Chrysler or the "Clearwater" head made by Odessa Cylinder Head in Clearwater, FL. Both cost in the neighborhood of $500. You can find the TUPY head in junkyards for around $50 and about $300 to get it reconditioned. You can look down the oil filler cap with a flashlight and see the TUPY molded into the metal like this picture shows:

 

I would push him to get have a real mechanic look at it and give a better diagnosis before jumping straight to asking you to pay for an expensive engine swap. Leaking and old oil isn't very descriptive, although the 2000 is known for cracked heads and you have to make sure any replacement it's going to have the same flawed head. If it's just a bad head or head gasket, that's significantly cheaper and actually easier than replacing the entire engine. I also question if your son and friend can't figure out what engine they need, are they capable of doing an engine swap?

Personally, I wouldn't recommend putting that much money into a 20 year old vehicle with a max bluebook of $4000 without knowing what the rest of it looked like. If the body is rotten, it's not worth it. If the engine truly is blown, I'd look for a lower mileage used engine first.