If I may...
I've already chatted briefly about this privately, and I offered this solution:

You need an RPM switch to have the D-jet step to a richer map.

Anything in the way of an adjustable shift light has the circuit; MSD make specific modules for this, also.

What you do is run a relay and a Pot. At ~4800 rpm, the circuit to the temp sensor is cut and replaced with one routed through a potentiometer. Pot is trimmed to make a reasonable step. This is like the IPd box, but only cuts in when you need it. The trick to making D-jet work, is to keep the vacuum to throttle opening to RPM map similar. No different than later domestic speed-density systems. With enough switches you could tailor a whole new map... which would be impractical, but basically, if it's close, this should be a solution.

Here is a graph I did of using two steps.

Non proportional, use at your own risk, etc, etc but it helps explain what I'm suggesting.