What you've identified as an "LNP-057" is actually an "INP-057". It's made by Nippon-Denso and is the same as the "N210H".

The N210H is used in the SOHC 10:1 compression ratio engines (Diamante), while the B210H (also designated INP-051) is used in the SOHC 8.9:1 compression ratio engines as found in Monteros.... and yes, the N210H and INP-057 injectors will run rich in a Montero engine.

Here are the injectors you should be able to use in a Montero SOHC 8.9:1 compression ratio Mitsubishi 3.0L V6 engine:

89-94 Montero 3.0L V6
97 Montero Sport 3.0L V6
89-90 Sigma V6
90 Pickup V6 (some - not all - to 5/90)
91-92 Mirage 1595cc 4 cyl
88 Galant V6 (some cars - not all)
89 Galant 1997cc 4 cyl (some cars - not all)
90 Eclipse 1755cc 4 cyl (some - not all - to 5/90)

Frank

'89 [color:"white"]G-Raider[color:"white"] [color:"black"]Supercharged 3.0L, MegaSquirt 2, lockup A/T, 2.5" exhaust, 172k, Cibie H4s/Oscar SCs, Hella Micro DE fogs, Cobra CB, Superwinch hubs, LSD rear/Aussie Locker front, Bilsteins, Lifeline AGM, Rust-Oleum