I believe the Horizon is still available.
I own an older model of it. Here you find a scan along with the tractor rail of the 135 film, that gives you some impression of the frame format (57x24mm).
This is a scan of 3 frames in a row with which I tried to "stitch" a 360° pano on one strip of negative film.
Any digital camera could do pretty much the same thing with the aid of good stitching tools. PTGui or Panorama Studio comes to my mind. But there are much more and some of them are really good, though some are crap.
As for the operator: When you don't have a nodal mount - and in most situations you don't need that - then try to use a tripod at least. If you don't use a tripod then try to turn yourself around the lens of the camera instead of turning you around and the camera around you. Aim to have the same perspective when you turn around.
When I do that than I imagine having a tripod with which I'd have to turn myself around the camera that is mounted on the tripod.
Don't use AWB, use a fix white balance for all images. Or use RAW and care for the white blance later.
Use the same settings for all images. Use the M program and avoid Auto-ISO. When the situation is difficult then meter all directions first, use some values between the maximum and minimum and try them. Again, RAW is helpful here. Then shoot all of the images with the same settings.
Avoid polarizing filters!
And go for it :-)