As far as the rings go, I would highly recommend the Signature Zee rings, they don't require lapping to prevent stress on the scope and will not leave ring marks on the tube. MidwayUSA has these on sale right now for $25 and just incase you have alignment problems, can get the offset insert kit to allow you to mechanically center the scope then bore sight it without ever touching the turret adjustments. My .204 Ruger handi was way off when I mounted the scope, but using the +/-.05 inserts was able to perfectly zero the reticle without turning the adjustments. This keeps the image optically centered where the best possible resolution is possible.
The height just depends on the scope power rings size and position and if it interferres with the hammer, it is usually the determining factor as to medium or high ring selection. Some of mine use medium, some use high. High will work for sure, but I like mine as low as possible so I try mediums first. Sometimes the hammer just clears with the mediums, you need a few thousanths of clearance when the hammer falls dues to overtravel, or you'll end up with marks on the scope. I like to mount mine without the hammer extension, if possible.
Midwayusa