I actually didn't test getting solder to stick to the brass. But it definitely worked. It was a pretty tight fit, so hopefully it wicked in well enough to get a good seal. I think it should be fine, but I haven't run water through it, yet. That'll be the real test.
I know solder should stick to brass just fine, which is why I wasn't worried. It's part copper, anyway. My first attempt used a fitting that looked like brass, but it was actually gold-colored aluminum, and that didn't stick worth a darn. This one worked really well on the first try.
I actually set the coil down into my pot to get the height right, opening it up a bit larger than originally coiled to account for the diameter of my pot. The first coil on top should sit right at or just below the water line in the pot. The hand-bending to open up the coil is why it's not a perfect coil. But it should get the job done just fine. Then I dry-fit the fittings together to see where I wanted to cut my copper pipe for the inlet/outlet locations. I didn't want them so high that a connected hose would tip the chiller over. The one angled down should rest against the lip of the pot, when the hose is connected. That'll support it so it doesn't tip. The other connection, well... I would have wanted to do that same thing there, but I didn't have extra elbows to angle the output down. But it should be just fine.
You mentioned the chiller you built is too tall for a 62-quart pot..? If it was originally made for an 8-gallon pot, like mine is, that's 32 quarts. Yours is a 15.5-gallon pot. How is it too tall..? If anything, I would think it would be too short.