First thing first, throw the Power FC in the trash can. You're talking about implementing systems into the car that it just cannot do. That and it's 2017, not 2001.
Right, I have attached a few photo's of my own setup here.
The sensor in the gearbox spins as the drum turns. For example, 1st gear may be from 0.5 V to 1.1 V. 2nd gear may be from 1.1V to 1.6 V. You set the parameters in the ECU.
The strain gauge I have uploaded a photo of it and the specs of it also. It's the "motorsport systems" unit (The Australian one, not the Motorsport Systems from the UK)
These two items add roughly another $2,000 AUD to the total cost of the box but means no liftings going up gears, just pulling the stick.
Here is a link of Craig Loundes using the same nob coupled with a Albins box.
Motorsport Systems gearnob specs MS-GLCA1 Datasheet V1.4.pdf