Custom Firmware for Taz 5 with 700mm zAxis and Aerostruder

Hello I have a Taz 5 with a 700mm zaxis. I had a toolhead fail and decided to try an aerostruder. I am having trouble compiling the firmware to flash the new settings. Can you help me out.

I need to change,

Zmax to 700mm
Zsteps to 400
And then have the code for the Aerostruder