Buy a high quality, adult-sized stock for the 7mm-08. Absolutely no need for a new rifle.
That would be my suggestion as well. I might make it a theme to upgrade the 700 on different occasions. A new stock and trigger might be nice rather than new gun. Later a longer mag box and new barrel-action job might be on the table. I would much rather have one really nice rifle than two cheaper ones.
As far as the caliber choices the 6.5 offers great ballistics but doesn't really excel until over 600 yards. The Creedmoor is popular because for the first time manufacturers combined a short action with a platform designed to shoot the high BC bullets. For many years anyone shooting 6.5's would have to change the barrel and modify magazine size from stock configurations to take advantage of the better BC bullets.
There's nothing wrong with a 270 but the 7-08 offers the benefits of a short action and a wider range of bullet choices. It's probably my favorite caliber and I can't think of anything it couldn't handle that a 270 could.
