Need some advice to get my setup operational

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Hey guys, sorry in advance if some of my terminology is off, i'm still learning. I'm trying to to get this new to me stainless steel European reflux condensor safe and ready to use. It's missing a temp guage on the kettle, the fitting where one would go is smooth-tapered to 3/8"ID. I also need one up top on the reflux column and the ID is 3/8" smooth aswell , the column is 1.5" wide. Hoping someone knows where I can find them!

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I also noticed a few small cracks along where the 90° elbows are welded from factory so to be safe, I'm looking to silver solder the area without buying a big roll of stay brite 8, I'd like to make sure its still a "food grade" solder/flux, the only one I've been able to find in a small amount (1/2 oz) is "Harris SBSKPOP Stay-Brite Silver Bearing Solder Kit" and it says it has 4% silver content. Has anyone used this product before on stainless? Or if you guys have other suggestions on what to use please let me know! Thanks in advance.