GAIRLOCHIAN on this forum makes a no-gunsmithing mount for the Number 4. It is cheap and it is said to be tough.
When I was running the gunshop in Wainwright, I used to get the S&K out of MilArm in Edmonchuk. Excellent mounts.
I believe that Higginson Powders stocks them as well. Good prices.
Hope this helps.