Just out of curiosity why not rebuild the one you already have? Did I miss something is there a hole in the block? Did it spin a main bearing or something? If the crankshaft really is damaged it should be able to be turned by any decent machine shop and you would be able to run oversize bearings to make up the difference. Unless there is something else wrong with the crank.
The only thing that I am not sure of is if there are oversize bearings available for this engine or not. It sure would make it a lot easier knowing that the crankshaft signal would be correct because its the one that came out of the SUV. I am not sure why your mechanic did not bring up this option?
P.S. Thanks for the picture Buster28 its nice to know now that the 3.2s have 4 bolt mains.
1988 trooper, 5 speed, 2.6L, 180,000 miles
1992 trooper, 5 speed, 3.2L, 144,000 miles