I am about to embark on a re-restoration of a 67 123GT that was my daily driver until about 10 years ago when I oiled it up and put it away until I had time to deal with some rust issues. The car is complete, mechanically excellent and running, and solid except for the front, driver's side floor area. I have ordered a new floor pan and cross member from Olof, and the rocker and transmission tunnel are solid, so lots of good metal to weld into. However, the front side member that runs from under the seats forward and up under the bulkhead is almost non-existant where it makes its upward curve. I haven't been able to find a new replacement part, and it seems unlikely that I could find a good repair clip from a wreck. Has anyone dealt with this issue?

Are you talking about the frame member? Can you take a picture and post it? Have a look through my build thread - I've replaced the front floor sections and I've cut off the frame section and am rebuilding them with heavier material. I have repaired a few 122's and 1800's that have issues in this area. The only section that is available is a reasonably crappy reproduction. As I've used them, I have chosen to not use them again. It's not hard to have a sheet metal fabrication shop make you up parts if you're confident in the measurement.

That said - there are many new parts coming on line all the time.
https://www.classicvolvoparts.co.uk/parts.asp?carID=3&cID=52&scID=226&page=A_Body_Panels

Part number BVP181L - I've not used this part but it doesn't look too bad - it's also really easy to build.

I prefer Brookhouse Volvo or other European sources to picking my way through Olof's catalogue sometimes. Olof often has a very good price, but Brookhouse has a wider selection of parts.

That looks like the right part. What gauge sheet metal do you use to fabricate your frame parts?

The originals were 16 ga. The ones I'm using are 10 ga but are overkill for what you're doing. 16 or 14 ga will be fine.