1959 Skyliner Frame Restoration

[59Sky]

I hauled a '59 Skyliner out of a field in November and while the roof, relay box and all the screw jacks and mechanism for it are present and functional, it was without a driveline and had spent what I'm guessing were the last 30 years laying frame and abandoned in that spot. The body is saveable, but the frame has a complete inner section about 16 inches long that dropped out when unloading. The frame is still continuous all the way around, which is holding the body straight, but I'm either going to have to chop out the damaged section and weld a new one in, or use the frame from my '59 4-door donor car and weld the center x-brace, which is in excellent condition into it.

I have seen just the X-braces for sale at swap meets/online and every one I have seen has had the sections of perimeter frame still attached at all four corners.

I'm new to perimeter frame car restoration (all work will be performed by a competent chassis shop, as I feel my welding skills are inadequate) and am wondering if anyone has any experience with converting a standard frame to convertible using factory bracing w/o resorting to custom fabricating a tube frame cross-brace, and if so, what I should be looking for. For example, my intuition would tell me the X-braces I've seen for sale have the perimeter frame segments so that they can be trimmed off to get a good fit between it and the frame, as hacking the new frame apart to adapt to the old perimeter remnants would introduce geometry changes in the chassis that would make proper alignment impossible.

Am I on the right track here?

*Edit* Added frame damage photo