Rebuild or replace with other motor?

My Jack is not well.

Pistons and con rods are damaged. 

Question is do I rebuild or do I replace with a different motor?

option 1 : replace with a 4JB1 - i believe these motors will slip right in with a little mod to the bell housing. I know it has less HP but its old school no electrics as such and i canget a Bare long for about $2000.00

Option 2: replace with a 4JB2 

Option 3: rebuild the existing motor. Not confident in the 4XJ1 motor. So not that enthused in this option.

Any advice would be a great help.Or any alternative ideas? 

If so any relevant detailed links or info would be a great help.

Thanks in advance guys.