The BA head uses standard spacing rockers with block/stands. The MC is the "moved center" head where it moves the intake valve over the open up the port. These use offset intake rockers. Not sure of the offset spec. I ran a set of BA heads for many years on a 408. There was previously done machining before I got them. They were angle milled to ****. Like 46 cc chambers. My flat top 408 was 15 to 1. These come with 2.08 valves and I think it was too much valve. They can work, but, they need a lot of work.
