Good Morning, Mike,
Of course, but if you think the mirror placement is the problem, it would make more sense to work on getting it set correctly. As Zhenya has noted above, it not difficult to determine if the taking lens is focusing properly. If your camera is achieving infinity focus when the scale so indicates, your problem is either incorrect alignment of viewing and taking lenses, or mirror displacement. I'd be hoping for a mirror problem, because that would probably be a lot easier to deal with.
Konical
Konical