A-yuh. That’s an old 30-degree Atlas all right. Looks just like the one sitting in a box under my layout somewhere, except for the color. I bought the Atlas roundhouse, too, and then upgraded to the 15-degree turntable:

I’ve converted the deck to a pit turntable by adding a bridge and sinking the whole thing into the layout:

If you have the room for a larger turntable, it’s probably worth the investment. I’ve put a lot of effort into the “pit-bash” project (and had a lot of fun doing it, too) but it’s not for everyone, and the alignment issues may yet haunt me for the rest of my life.
The Atlas roundhouse works perfectly with the Atlas turntable, but compatability with other turntables may be a problem. Some other turntables have their stalls at different angular separation, like 12 or even 10 degrees, and you’d need to fudge things a bit to get everything to line up. Also, it’s made for the 9-inch size of the Atlas, and once again you’d be doing some customizing with a larger turntable.
If you don’t mind a deck turntable (and there are prototypes for them) and your engines are short enough, then the Atlas is a perfectly functional and very reliable turntable with solid, repeatable indexing. My old one has seen 40 years, and was still in perfect running order. The motor kit is really noisy, but otherwise just fine as well.
I have a Proto 0-6-0 switcher, and it barely fits on the Atlas deck. My BLI Hudson isn’t even close. On the other hand, the Hudson won’t fit in the roundhouse, either, so other than turning, I’ve got no reason to put this engine on the bridge. If your engine roster is all short diesels, or small steam, then there’s nothing wrong with the Atlas. It will save you a lot of real e