Well I am certainly interested, as I could use both on my 45-120 now to see how much it takes felt recoil down, then I could use them on the big gun as well. PM me with costs.
Diameter and size really don't matter, the stock hole fits a 7/8" recoil reducer pretty tight, but I could always make it larger. I think my 45-120 is pretty well balanced, so about equal weights would be good, but the barrel mounted one would be moveable so thats a plus. Might look a bit unorthodox, but heck the whole gun is.