Sorry if my question was confusing.
I'll try again. Level(up or down), or inline(fore and aft) with the pivot point of the mast/tabernacle? Correct me if I'm wrong, but the geometry seems more dependent on the latter than the former.
It would be helpful if you could get some photos of your set-up posted here.
"In line" with the pivot point is the term I would use. The Mac boats have flat cabin tops and the baby stays are easily connected in line with the pivot point of the mast which is the same height as the lower connections of the baby stays. Also there is plenty of width between these connections and the mast tabernacle to attain the lateral stability needed.
My O'Day 222 has a raised cabin with side decks. Although the cabin is flat enough for baby stay connections, it really isn't wide enough for adequate lateral stability for my mast. The wider these baby stays are, the better the stability.
To solve this problem I mounted hardware on my side decks for what I call pivot bridles which are made up of braid line, stainless steel rings, and snap hooks.
The rings on these pivot bridles come "in line" with the pivot point of my mast tabernacle pin when my baby stays and Gin Pole bridle is attached to the rings. My first pic only shows one of the pivot bridles for the sake of illustration. It doesn't show the ring in line with the mast, but it is if you're sighting it at the proper angle at the beam, perpendicular to the centerline of the boat.
You can stand on either side of the boat's beam, perpendicular to the centerline, and actually sight the rings and the pivot point of the mast.
These pivot bridles can work on most boats in mast raising/lowering over the bow or over the stern depending on the location of the side chainplates.
The mast yoke or anchor point for my baby stays in the second pic will work on any boat. Mine hinges around the mast with a dog to tighten up on it, but this device doesn't need to be too elaborate. A mast yoke can be made to fit snug on the mast with a long bolt and a screw type knob to secure it tighter to the mast.
I suppose that one could bore a hole through the mast and use a nut and bolt to hold a tang on each side of the mast and you could leave it attached. I think I'll pass on that one.