I have a tactical rifle with a 50mm Schmidt on top. I use an older X1(A1?) for it and it works fine.
I had looked at the "Just One" as well but the scabbard on that was significantly smaller and wouldn't fit the scope/rifle combination. The scabbards vary a lot in size.
If you can, I would try to test fit the rifle you plan on using into the scabbard before you buy it. Make sure the fit isn't too tight to get the gun out easily.
+2 on the "Try it to test the fit". I have three Eberlestock packs. The scabbards vary in size. Typically carry a "traditional style" hunting rifle with low mounted 40mm scope and flush bottom metal. One of the packs, (X3 Low Drag, I think) the scabbard is so wide that a traditional rifle tends to "slosh" back and forth until you really cinch down the straps...
If you are doing a lot of brush busting with the pack on, be aware that pine needles, twigs, leaf litter will fall into the scabbard. One year in Colorado, pulled my rifle out of the pack at end of day and found a section of scrub oak twig stuck in the barrel.
Most of the Eberlestock scabbards have a clean out zipper at the bottom of the scabbard. Need to occasionally pop that open and remove any trash that has collected in the bottom of the scabbard.