Cheers.
I forgot about the original res clamps. I use different ones that don't wrap around and they put the res closer to whatever it's screwed into.
If you use the res vertically, don't have the inlet at the top. That's where you fill and bleed it, so use one of the lower ports by just running the tube down the side into a 90° fitting.
Horizontal looks like it could work with a couple of 90° fittings.