Mr. Chasseur:

Given your choice of chamberings, the first consideration will have to be extraction of the rimless case. Generally speaking, single shot actions work best with rimmed cases. The one commercial action that does have a reliable rimless extractor is the Ruger #1. In fact everything about the #1 is reliable, which is a significant feature considering how far you are walking back in the hills.

The take down design can be as simple as the set screw lock used on the Stevens 44 and 44-1/2, or some variation of the cross pin lock. They all do pretty much the same thing. The key to a good repeatable take down set up is a good barrel fit with as much metal contact as possible. This means lapping the action face square to the threads and cutting perfectly formed barrel threads. You need the barrel to be solid as soon as the shoulder comes up tight. Any mushiness to the fit and you will be plagued by premature wear.

Also, you are going to need removable scope mounts, although it is possible that with a quarter turn interrupted threads you could do with fixed mounts.

Best of luck on the project!

Glenn