Why ruin a perfectly good Ford with a cummins...:woot:.
I dont think there will be any kits available, not enough people looking to do it to that vintage of a rig, so the companies wont make them. You can get tranny adaptors, and motor mounts, but I think you will end up having to mount it all up.
Or, you could build a good running IDI. Shave .030 of the tops of the pistons (drops compression ratio), use head studs, balance everything, clean up the heads some, clean up the exhaust manifolds, fab up a custom turbo setup using a OBS PSD turbo, buy a Moose pump, get G code injectors. There you go, it should be good for around 300 hp, and you would be in it for less than a cummins instal, and you would be sticking with a good ole IH motor.