I use a welder and Weld a nut on the broken bolts if they are flush or better or slightly below the surface. They come out pretty easy, just need to get onto them. Easy put works as well, but keep a super hawk eye on your angles so you don't go off course and hit water. The easy out way is not for beer drinking time, the welding way works with beers.
One other note. The absolute number one screw up people make with the vvt set up is missing the dowel on the camshaft. It goes on pretty blind, so I like to pull it and put it on a few times to be super sure. If the dowel misses the hole, it will at best misfire like crazy, at worst, smack some valves. Other than that, make sure you get all the coolant out of the head bolt holes before bolting down the heads.
Good luck!