Crank Sensor

As I understand, you want to install an earlier 1970's distributor for spark and thus need another crank sensor so the PCM will continue controlling fuel, without knowing the difference.

Unlikely a TBI engine would use sequential injection, so all the fuel controller needs is probably just an rpm signal. That is how Holley Pro-jection works. They just monitor coil- for the rpm signal. You might simply need a 5 V "tach" signal. Look at aftermarket tachometers, or maybe using the GM coil that connects to their 8-pin HEI module would work (wht wire is tach).

If you do install a new crank sensor, it might be hard to use a 5.2 Magnum flexplate w/ "toner ring" unless your transmission bell housing has a mount for the sensor. Also, if like my 3.8L, the pickup slots are not uniform, but rather ~12 fairly wide slots of varying width that the computer decodes. I doubt that signal would be at all like the one from your factory TBI distributor. A 36-1 wheel might work better. I put one on my 65 small block, w/ a sensor off the water pump bolts (behind pulley). I made brackets for both a Ford VR sensor and a Mopar Hall-effect. See my post w/ photos (haven't taken it further yet).

You need to see what pickup wheel and signal is in your TBI distributor and make a crank sensor that gives a similar signal. If just 8 notches like a 70's distributor, then I would think simply using a tach signal off the coil would work the same. Anyway, I agree with Kit that if above is your plan, it is going backwards in technology.