I have a set of MSDS /6 headers and it appears that my handbrake cables sit right on the headers. I haven't started the engine yet cause they will obviously melt. Anyone else have this issue and if so what did you do?

I have them on my 3.0. The cable on the driver side does when I have the car lifted up and the trailing arm is down. It ends up touching the bottom of the headers. I have to make sure when the car is on the ground the cable is positioned over the header.

Yep, once your 914 is on the ground it's no longer on the header.
If you're worried about it you could run the cable through a section of fire sleeve.

https://www.aircraftspruce.ca/catalog/appag...qfiresleeve.php

Thank you to everyone for the advice. I had never looked with the car on the ground. The cables now are not resting on the headers.

Just for future reference- does fire wrap work even if it is resting directly on a high heat source like a header?

Likely no, it's meant for close proximity and temporary contact, but the correct hose with the correct clamps is what the FAA calls "fireproof". Constant contact with a header the cover might not fail, but what's inside might bake till it fails.
If it only monetarily touches the headers you will be fine.