Hi minibn> You don't mention how old your ram is. The older he is the less likely his horns are to grow much further. If he's a shearling then they have a lot more growth to go. I agree that he should not be used for breeding as horn shape is hereditary to some extent. Horns can grow right into the bones of the head or face, or into the eyes if they are pointing that way, which is ultra gruesome
To work out how far the internal blood vessels reach, hold the horn in your hand - where it feels warm to the touch there is a blood supply present, where it's external temp then you are clear of the live part.
Very sensible to let someone else do it, but do make sure they know what they are on about. If you decide to use the heat treatment, you must protect his face and eyes with an asbestos oven cloth or similar.
I think the stretcher bars would only work on a young animal.
The cheese wire saw is readily obtainable at hardware stores and not as hard as all that to use. The trick is to keep your hands wide apart, so the wire is almost straight. Again, the eyes must be protected from the filings. If you were to do that, this particular horn could be cut at an angle, so it sits further from the face and has a bit of a point towards the outer side. It might be a temporary fix to file the inner surface of the horn to give it the same profile, again protecting the face.
On a non-sedated ram, just having one person to hold the head firmly is enough, without having to use sedation - it is only painful if the cut goes through the part with a blood supply.
Looking again at the photos, the deformity looks as if it may have been caused by someone dragging the ram along by the horns several times when he was young.