K20 cab mount bracing with rotted cab mounts

[Rg500gamma]

I will need to install the braces to keep the integrity of the cab square before I remove it from the frame. Should I use the door hinges to the floor and the b pillar door lock to the floor as my reference and then left to right frame brace with a level on it to ensure it is square so I can pull it off the frame and leave at that to do the floor replacement ?
Love to hear what other methods have been used.