That's probably the best idea, make sure they don't powder coat the area of the clamp that the bearing presses up against because the powder coat will wear over time and cause the head bearings to come loose and it will keep doing it untill all the powder coat is worn out from between the bearing and the clamp. Talk to the guys that are going to powder coat your parts and make sure they do not coat any of the machined portions of the clamp. When you get the frame back there is a lot of prep work to be done before you can put it together. Make sure you chase all of the threaded holes with a tap so they are clean of powder coat. Be sure to sand off the powder coat from all of the mating surfaces like the engine mounts and so on, or you will have assembly problems and things will come loose over time as the powder coat brakes down. Did you ever see the episode of O.C.C. where they got all of their stuff back from the powder coater and they were beating it all together with hammers and everything was stuck, I laughed my ass off those guys are supossed to be pros.