[T2] Using a later FI system on 75 bus?

[MUTS]

We have a 75 bus that needs a FI harness replacement (cracking, wires to 
connector to double relay goofed up, bus won't start due to this we 
believe) and Kyle Automotive Sp will make it for us $100 more than the 
76-79 ones.  Has anyone switched to a later than 75 FI system from a 
75?  Do you know of where I can ask if someone did?  The 75 has a 6 pin 
connector to the Flow Meter while the later ones have a 7th pin for the 
temp sensor in the airflow. There is a unique connection to the air 
distribution box (throttle) that detected full throttle, or was it an 
EGR system no longer attached?

The "brain" is unique also- and a later one I have or can find more easily.

We worry about getting any spare replacements such as the Air Flow Meter 
or the "brain" unique to the 75; the later ones are more available.  
Advice accepted.