You're right, the 2.8L was used during the development of the 4.0L to fill a niche as 84-86 had such awesome engine choices. Probably the easiest swaps the OP could do would be the 3.1, 3.4, or 4.3. None of which the OP has, but more along the lines of cheap and easy. 305 would still be the easiest of the two swaps imho, especially if running a carb setup. Not a lot of room in there to begin with, but lots of guys have shoehorned them in. OP, just start googling and reading before you jump into a swap.

 

yea I'm going to be searching and reading up a lot about the swap. and i would like to find a wreck 4.0 cherokee so i could use it for parts and drivetrain out of it. oh and the boat i will be pulling is a 16ft. fiberglass ski boat, it will pull it down the road its just lackin the power to go up any kind of hills or bridges in town. and I am pretty sure the only reason why it can pull it now is those 4.10 gears and 235's