I see 2 possible issues.
1) Somewhere in the early 90s (I believe it was 92 or 93), Dodge changed the motor mounts from the old mounting ears on the block to flat plates with threaded boss in the block. You will need the motor mount brackets for which ever motor your using.
2) I believe the Magnums were all port injected instead of being throttle body like the LAs were. I believe the Magnum was also when Dodge went to the OBD II computer. You may have to upgrade the wiring from OBD I to OBD II. I have no ides what that involves.
I have a 91 Dakota here and its a LA with OBD I and I have a 93 and its a Magnum with OBD II, I'm not sure if the change came in 92 or 93. Gene