5.7 into a 90's vehicle difficulty?

I have a 2004 5.7 Hemi and I am wondering what kind of challenges would need to be conquered to convert an older pickup (To be determined) 1990-1993 Ram, Dakota, or Durango, with a small block and automatic, 3.9, 5.2, 5.9, or even a 4.7. I'm considering options for a project for a 75 D100. Body transplant on a newer frame, suspension, steering, drive train, and driveline. I'm mostly wondering about the electrical end of it. Nightmare, or easy peasy?

Have you seen what Holley has to offer now? Holley Hemi Swaps

Thanks for the link. Lots of stuff that I didn't know was available.

I've been wondering if they'll make a kit for the W series trucks. A lot more do deal with up front