I am bit confused why anything from the k-jet would/could be retained. Outside of the in-tank lift pump, potentially the fuel pump relay (unlikely) and coolant temperature sensor...only the tachometer feed would be compatible.

You will need to figure out a couple of crucial incompatible item and Turbobricks might be your best place but Art B could potentially also help. You need the tone ring and sensor from the 940 axle (likely the whole axle) and wiring to feed the ECU that signal.

If you are NOT keeping the '79 transmission you will have to figure out how to feed the speedometer or more likely replace it as it is cable driven.

I am sure you also realize that the O2 sensors are also incompatible but I would hope you are going with a custom exhaust instead of splicing into the tiny B21 pipe.

My 1979 wagon is still my favorite daily driver ever so this sounds like a great project.