you don't mention the machine your doing this on which can play an important role in determining what would be best . If the mill is of quality then interpolation with a 7/8 or 3/4" end mill is the most efficient way to making your hole .
Even the best boring heads will produce poor results if not set up properly . I'm guessing that your bar is sticking out a fair bit more than it needs to , and the first thing I would do if that was the case is to chop the bar down and have it stick out 1.1" from the head . If you want a quality head then d'andrea makes some really nice stuff but it's costly