that's an OBD-I computer right? I don't know how easy/hard it would be to get a computer to run it, but otherwise, it'd be very simple. Magnum blocks have the LA ears so they can go into vehicles that had LA engines.

don't be hard up for a motor out of an R/T truck because they all got the same motor. the 5.9 in a panel van work truck is the same as the 5.9 in a Dakota R/T. (for the same model year...there's debate that cam specs changed from one year to the next, but across the same model year, they were all the same motor, and honestly, any cam changes was only a difference of a few Hp and not worth enough to be getting picky...especially when you can get the original cam re-ground for about $100 to just about whatever specs you would want)