Picked up a set of Spirit goggles and went about modifying them to look like GB 2goggles.
First up, disassembly. The lenses are glued in on an inner indexing ring, but the outer ring isn't glued. Twisting the lenses off with a pair of channel locks worked pretty well. Just trim whatever is left behind flush with the inside.
The rubber face bumper pulls off with gentle effort, as super glue doesn't stick to the rubber as well as it does everything else.
The inner frame took some prying to separate the glued sections. A little heat would have helped, or super glue debonder. If I did a second pair, I'd use debonder.
From there, I used crydrk (Thingiverse]'s excellent 3D Printed GB2 goggles as a baseline for lenses and other small parts.
Here's my remix of his parts, for use specifically on the Spirit Ecto Goggles: https://www.thingiverse.com/thing:3096026
And here's the finished product. Note - The rivet that holds on the top face strap is very soft steel, I snipped it off with flush cutters for painting, then replaced it with a 3/16 Aluminum Pop Rivet.
Note that stickers aren't on in these images, as the paint was still not 100% cured (48 Hours, typically.)