Longines Conquest 18k 9001 Bezel Issue

I recently picked up a ref. 9001 Conquest from the late 1950s and was quite pleased with the purchase until I realized that it was missing the original bezel. The bezel on the watch is quite a bit smaller and thinner, and the slightly different color/hue suggests that it likely isn’t solid 18k gold. The watch was advertised (on eBay) as being 100% original so I have the option of returning the watch, but before taking that step, I wanted to check with members more knowledgeable about Longines if the bezels on steel/gold cap beefy lug 50s Conquest models have (18k?) solid gold bezels.
I’m leaning toward a return and then keeping an eye out for another clean example of this reference but the dial and case back/enamel on the watch I purchased are in really nice condition. Any thoughts on a replacement bezel would be appreciated!

Not personally used them:

https://www.watchcaserepair.com/