I really like the 30cal too and have a Gibbs, '06 and RUM. However, for the distances you are planning, you may not want all that recoil for plinking.
I am on a big 6.5 kick since Hornady brought our the 140gr SST. What a wonderful bullet. Very high BC (.65 to .7) and should be deadly on the size of game you are hunting. Match accurate too.
LR ballistics/wind drift are so also far superior to the mid weight 30/7mm/338 bullets. Cost of these bullets are also very reasonable.
So I would suggest you go with the 6.5-06 or improved/Gibbs. Try and get 3000fps. May need a 26" barrel with 1 in 9 or 8.5 twist of moderate taper.
Recoil would be very mild by hunting standards and with a muzzle brake
, target shooting will be very enjoyable. This rig could be used for target shooting to a mile.
I am working on a wildcat I call the 6.5 Mystic. Based on a modified '08 case throated for this SST bullet, the accuracy potential has been very good. Muzzle vel has been a bit low at 2725fps (25" barrel). No problem for plinking but I would want more juice for hunting.
The 6.5-284 is also a very well designed case. It is not as easy to feed as a standard case and brass is much more expensive.
Another choice could be the 280Rem. A friend shoots 168gr MK out to 1000m. Very nice shooter and would hit a bit harder (?). A little more wind drift then the 6.5.
Wouldn't choose any cal smaller. Just not enough bullet weight for me at 700yds.