Inliner Tom S. (6inarow) cast a batch of smooth top ones with the 216 type 2 hole mounting that have enough material on the top to engrave any desired pattern etc. A 4 bolt aluminum one would have to be a one off and the last time I checked the material alone was over $300.00. With a piece of aluminum that big you might as well just make a crossflow head with it.
Spraying cast aluminum looking paint on a tin one is about the only way to keep 4 bolts.
