Purely for deer I'd get the 7mm-08. It shoots flatter, kicks less yet kills just as well as the 308. With a 140 grain bullet it is hot death on deer sized game. I have one in a Browning bolt action and IMHO it's just about as perfect a deer cartridge as you could ever want.
there is no such thing as overkill.
So a 700 nitro express with a 1000 grain bullet at 2000 fps still wouldn't be overkill for a 160lb deer?
Sorry but "YES" overkill does exist. Now where overkill starts is a highly debatable topic but trust me, it's out there.