Doing a good job of installing a brake only takes an hour or so. If the 'smith's lathe is big enough, you strip the rifle to its barrelled receiver and take it to him when he has a time slot to do the job. Make an appointment, so to speak. He will turn and thread the muzzle, fit the brake, and touch up the crown as needed. Smaller lathe could require the barrel to be removed from the receiver. This increases the complexity and cost of the job. Depending on the brake, it may need to be reamed or bored for the caliber.
Appearance is all very well, but having a brake really changes the shootability of the rifle. Recoil is reduced, of course, but you will also be able to see bullet strike through the scope. There are those who make a big deal about the increase in blast, of course.
I have never heard of a clamp on brake for a 700. A brake really needs to be properly fitted, with its bore absolutely co-axial with the bore of the barrel.