Found a new air galley for you: https://jdm-car-parts.com/products/air-galley-for-datsun-240z
Kidding! Unless it's a must have for a concours Z.
You might try the simple and cheapest #5 option first. I would try to jam a short 1/2" long piece of tubing (or bolt shank) that tightly fits in both ends of the broken tube, to hold together in alignment without completely relying on the JB Weld. Might be worth a shot before spending a lot of money. It'd be a shame to trash all the work you've done so far getting that stock appearance, looks great. If you need any mechanical help, feel free to contact me. I'm just an old retired guy with lots of free time lately.
Yeah, I'm satisfied with the MSA 6 to 1 header, good clearance over speed bumps, unless you go too fast. For performance, there are better ones, but this one suites me fine. Muffler Tech is still there on Florin Road, a bit of a drive from Roseville with an open header, but the cops will understand, right?