Yes it can be done, but it is not real easy. If your Monti were a 3.0 it would be set for an injected engine.
What you will run up against is getting and swapping in a transmission from a V6, if yours was an automatic this would be straight forward.
You then need to change your fuel system over for the injection. Convert the engine harness over and then determine whether the alternator P/S pump and such get swapped in. Exhaust manifolds, etc.
That just touches on the work involved.

It is do-able but it is a big job.

Cheers, Charlie
If It ain't broke, Modify it!
87 Montero turbo Converted back in Spring1989
95 Montero SR 3.8 DOHC Only one?
93 Pajero 3 door 6G75 Mivec with paddle shifted 5 speed
Then a Gen2 SR with full coil independent suspension.