Recessed bridge questions


I'd like to use a tonepros TOM for a recessed bridge and string-through set up on a tele style build.  My question is how deep should the bridge rout be?  Also must the bridge rout be arched to match the radius on the bottom of the bridge or can it have a flat bottom?
Haven't used one of those bridges yet; but when you order the body you can specify that bridge routing for a $15 dollar upcharge and that's definitely $15 you don't want to try to save by doing yourself....

Note: I don't see any Tele bodies with this routing in the Showcase (they recently added a few Strat bodies), so you'll have to custom order...