This room for the hammer is over blown. They make a hammer extension that goes out to one side or the otehr so you can easily drop or cock the gun. Mike's makes one version of it. As long as the hammer has room to go past the objective you don't need room for your thumb too.
As to mounts, it all depends on which scope as to what rings you need. Decide on the exact scope and you can get a fit chart for the make of rings and bases that will tell you if they work or nor. For example, Leupold 3x9x40, Leupold rings and bases; a low ring works for sure as that is what I used. If you use Weaver style bases and QR rings, use Medium rings. Both of those mounts have LOTS of room for the hammer.
Waever Base so you can see open sights with scope removed.
