Help! Trying to mod vintage Phase 90 for bypass, led, power

[jmfranc]

I have a 77 MXR Phase 90 that I amputating into a new case so I don't damage the original. Like the vintage Distortion + I modded with Waldo's generous help - I want to add true bypass, an led, and 9 volt plug for my board power.

I would do it exactly like the Dist + but there's one extra wire coming from the board - a grey one.

Wires:

Dist + has: orange, yellow, black, red, and purple

Phase 90 has all the same but also has a grey wire that was wired to the center lug on the pot

And the Phase 90 has one pot and an extra grey wire. What do I do?

Bonus question: I read the Phase 90 used a reverse 500k pot. Can I use a standard pot and not effect the sound in some way?