Cab floor repalcement

[orange66fleet]

I have posted some details on my 63 or 65 cab selection for my truck. Now the problem I am have is the floor to the 63 is gone. I have no pictures, still no camera. The 65 is a southern cab and only needs minor repair. My thought is to cut the entire firewall, A piller then cut where the rear of the rocker meet and finally cut the lip where the floorboards meet the lower back of the cab. How does this sound to the seasoned pro.