Bully,
If I may suggest, the .223 is a good idea to pursue, however IMHO the PURE .243 IS NOT. I would strongly recommend you re-consider and go with a 6mmbr. It is a much more accurate cartridge than a PURE .243 which is a great caliber for hunting, but doesn't cut it when shooting Benchest. AS far as the repeater aspect goes, it all depends on what discipline you plan to pursue. And I shoot both single shot and well as repeater calibers but STRICTLY off the bench. My two most accurate shooting rifle are a 30BR (Remington 700 Single shot) and my Savage 6mmbr which is also a single shot. But my repeaters also shoot very nice groups all off the Bench. I must defer to others on this blog as to what's best in other disciplines of shooting. But also remember if you want to compete, there are weight restriction and other specific rules that may well govern the rifle you are permitted to shoot.
But do consider NOT building that PURE.243. I have a good friend who made that mistake and is now having to spend the extra money in having his rifle barrel changed/chamber to a 6mmbr or a 6.5 Creedmoor, that after he shot my Savage 6mmbr after spending alot of time and money trying to make that new .243 shoot what anyone would consider NOT a good group when comparing it to other well established calibers used in competition. Even his Gunsmith who is an accomplished shooter himself and wins competitions left and right, put together handloads for my friend's and those couldn't keep up with my 6mmbr. Don't waste your money on something that won't give you the best results. Ask yourself, how many PURE .243 do you see being shot in state and national level competitions????? (ZERO that I'm aware of) Why do you suppose that is?
Alex