Early A floor repair options?

Check out view photos by seansmopar, I scored floors from a old 66 race car..still the floors can use repair after I cleaned them up..but much better than in my car..I cut the floor out in two halves, drivers and passenger..then cut them into four parts so they are easier to work with..I have replaced floors before in a full framed car but never in a sub frame..Do I need to brace the car say if I cut from front floor near the firewall to near the hump under the back seat..just on a single side.. I plan to work one side at a time..I'm afraid the doors won't close properly if I cut that much out..I have the car on stands under the diff and under each control arm.. I'm just hoping to not get any body movement without a brace between the doors.. Do I need it? Thanks