I use clamp on for all of my builds anyway. Set screws work, but I like the idea of pulling a consistent contact around the barrel with a clamp on style, rather than pressing a gap open at the bottom just to pull the top tight.
You can't always count on the dimple to position the block properly - it could be mis-located, or the port itself mis-located, or the port within the block could be mis-located. I let the gas block tell me where it wants to be positioned. I use an empty case with a spent primer to seal the chamber, then blow into the muzzle while sliding the gas block back and forth and turn it over the port. I can feel the position which gives the least resistance to flow, and that's where I lock it down. I'll then fire a few shots, put a timing mark on the barrel and block, pull it off, and look for any powder witness residual on the block or the barrel.