The instrumentation and senders and such in the 914 are so old an primitive that they are not compatible with any modern stuff that's out there. You can, if you're motivated, rig up a break-out box for some of the electrical stuff, and hook up circuitry that will read those signals and convert them into something meaningful to a digital system.
But you'd have to be
very motivated.
Although a 914 with a 1996+ engine swapped in, complete with all the engine management stuff, should be able to feed a standard OBD2 reader. There are quite a number of those out there now.
My feeling is that the Six swap is only a little more complex than putting together something to read and interpret the analog signals in the stock 914... (Though I might be exaggerating a bit.
)
--DD