Given the CIS stuff is bound to be getting difficult to find and $$, I wonder:

If the VW valve would work.

If a block could be machined and a needle valve be used effectively turning the system into a K jet where the shape of the air flow meter funnel dictates the fuel curve.

If a electric fuel injector could be used as a replacement valve. 80 and later SAAB and probably Volvo used this. It was located on the left inner fender and was called a " buzz valve " as is cycled anytime the key was on.

Granted, it is much easier to find the proper part and bolt it on.