Wait for other responses but I am leaning heavily toward the Power Stage. Cheap used "known good" but over a $100 new.

Three (common) things can cause the tach to drop to 0 on a running stall. The most common does not usually allow a restart (crank position sensor...CPS) at all without wiggling the wire. RSR, if the car has one but for some reason I do not think your car does. Finally, the power stage failing exactly matches your symptoms.

You can often get it functioning again, maybe only in the short term, by unbolting it and applying new thermal paste between the sensor and the body. It uses the whole fender as a heat sync but that only works if the thermal paste is in place. If it is original on car with that many miles, I would bet the paste is long gone.

Finally, check the easiest thing...make sure the battery cables are clean and tight. It is a long shot, cheap to check and takes only one tool...10MM wrench.