firewall replacement and other panels

[Krats1951]

I have 1955-59 and need to replace the firewall/toeboard and both step/rockers both inner and outer rear corners. left lower inner and outer hinge pockets. ? would you recommend changing one piece at a time of is there enough support for the cab to not flex with the firewall and step/rockers cut out at the spot welds?

[Kim57]

Personally I would do one at a time and weld in some temporary support pieces just to keep things from moving.
Kim

[dwcsr]

You will need to do some bracing, side to side and front door pillar to rear door pillar. Make sure you leave room to work.

I would do the firewall first. then steps and pillar pockets, then corners