For the SS hinge tabs, maybe a local metal fabrication shop could make you the missing tabs by copying the ones you do have. Probably be cheaper than trying to buy another set of windows.
As for the trim clips, you can get them from Altha Fastener in Altha, FL.. Ph 850-762-2179. Email contact is
john@althafastener.com . Item number 132745840289. The clips are $2 each.
I just installed swing outs in my Vega using the new Steele Rubber gaskets. I drilled the hinge bracket screw holes 11/16” out from the window opening pinch seam. That worked out good for me. I also trimmed the pinch seam height to a uniform 1/2” so the rubber gasket fits reasonably well. At the latch end, it took a bit to figure out how to align the latch base on the C pillar. An extra set of eyes and hands are helpful. Another thing, the gasket is too thick to let the latch sit flat on the C pillar, so I had to sand a dimple in the gasket but don’t sand through it.
Mark.