I physically rechecked both the sight (this sight) and my New Englander. The sight will mount. However, it might take some additional work in drilling and tapping two additional holes as opposed to one.
Originally my sight came from Thompson Center and it came with detailed instructions as to how to mount on various SideLocks. Yours should also come with these instructions and if not, or if you need additonal info, get back to me. .....
Be Safe !!!