Project advice

[JimmyCriswell]

I have a 68 longbed that I need to do some major body work to. rust primarily.
The truck is almost running but I had to rip all the interior out to repair cab. I have the entire left side patch panels ordered from topbanana and will begin. I have to replace outer half, lower front driver a piller, footwell, and some additional places. Passenger side has some rust but is in much better shape over all.

Question, what pieces do you start with to hold the integrity of the cab while working.

2nd question is best way to totally clean an undercarriage when I cannot afford a frame off right now. My goal is to do most of the labor work until money comes in to replace interior parts, wiring, disc brake swap, slight drop, etc...

Basically I want to stop the rusting process and keep it drivable until I can start to invest in replacing parts.

I can submit some pictures if wanted but I will need to learn how to reduce file size of pictures first and am unsure currently of how to do that.