Frame patch

[Sadlerracing529]

I tried searching and couldn't find anything on my exact question.
I have a 1963 c10 fleetside long bed and the frame directly above the factory rear coils is rusted through and cracked on only the bottom lip of the frame. In the future I plan to drop in a full rear frame/suspension kit, something like the kp components, or no limit engineering kit. But for now would it be safe to weld in a brace, and would a c notch kit extend far enough forward to help support this and make this truck safe to drive?
The reason I ask is the truck is road worthy right now other than this frame crack, and I would like to drive this truck here and there until I start the actual restoration and mods in a couple years.