a few years back, I dropped a 2000 durango 5.9 into my 65 coronet.
I reused my old 727, so can't help with the transmission, or the odbII system.
I had custom lines made local for the ps and a/c to hook into my cars existing stuff.
I did use efi, but not the factory type.
I reused the durango exhaust manifolds and that worked fine. with ps.
use the LA 360 pan, LA 360 motor mounts, or you can use the 318 mounts with a spacer.
Use the LA pan gasket or you have to fix the front and back of the pan to use the magnum 1 piece, as there is too much space for the mag gasket and it will leak.
you will need to find a van ps pump bracket. If you use the regular one from a truck, the ps pump gets tucked under the battery. it is not possible to pull the cap to fill it without taking the battery tray out of the car.
the throttle cable was a bit tricky.
how it attached to the truck was different then how it attaches to at least my car.
I took my old throttle cable and cut the end off. cut the eyelet open and then put the other cable after trimming it on.
I trimmed the square that held it into the firewall, square peg in a round hole type thing, so it seals there for me.