Well, I can give you some peace of mind hopefully: I had a 5 speed 89 V6 Raider, made for the Canadian market. Nfld salt did the body in. I found an 89 Montero AUTO that had lived most of its life in KC, and had been imported to Canada. I swapped the 5sp Raider's motor into the auto Montero. Zero issues. Straight swap. Done. And still going to this day (buddy of mine has it now - it was formerly known as Betsy III <img src="/forums/images/graemlins/lol.gif" alt="" /> ).

So... just swap the motor into the good Monty body, and call it good?

1991 HZJ77, 1999 KZJ90, 1999 UZJ100, 1992 M101CDN2
https://www.thegearheadproject.com/category/jdm-journeys/