NM you're a bucket full of information. I personally enjoy reading your post. I have a .243, a 6.5 CM and a 7-08. All are accurate rifles and would easily suffice for what the BigUncle has in mind for it. But bar none, my 6.5 CM will out shoot either the .243 or the 7-08 all day long. Now I'm not sure if its magic or is it because I spent a lot of time load developing the round using both the ladder test and the Statterlee method (which you helped me with) or could it be just magic!! . The .243 and 7-08 I just loaded until I found a load that shot a couple good groups and stuck with that. All 3 are production rifles.
I read the OP has no inkling to go with the 6.5 caliber but if he wants another great option for his intended purpose I hear the 6.5-284 is a pretty awesome cartridge.