7mm
You will be better off with the 7MM-08. If you go to the .284 you could have problems with feeding from the magazine. If your smith is good he should be able to tweak the feed rails to accomodate the .284 but that depends on the smith. Whether you stay with the 7MM-08 or go to the .284 you will need your smith to put the proper amount of throat in the rifle if you would like to seat 175 gr. bullets out far enough to not invade on powder space. This will greatly be determined by the amount of room you have in the magazine. Would be wise to measure the mag and see what COAL it will allow in your loaded ammo. 7MM 175 gr. bullets are highly effective even when pushed to very moderate velocities.