Love that head design. It's been bounced around since the late 60's. It put Dodge on top with the hemi big-blocks, then ford
used it in its small block mustang Boss motors and 351 Clevelands. It's been modified from full-hemi, open chambers to
semi-hemi closed(quench-type) chambers, but they all make high-flow, high horsepower. Harley Davidson(V-twin type motors)
use these heads for high horsepower. Head design allows for
largest valve size,but multi-angle valve heads cost more to produce and machine shop costs are slightly higher.