The valve angle is 16 degrees, you "may" get by with a standard 18 degree piston depending on what you've got camshaft wise.
As I mentioned before, they rocker arms are specific to them, despite Edelbrock initially claiming they'd run with BBM arms.

They still run a standard bolt pattern intake, you'd run a Super Victor or something similar. A friend is building 2 or 3 of them currently, with the off the shelf CNC ported heads. There is a lot of material left in them, their port seems like a waste of a great casting. I'll ask him if there was anything else he did out of the ordinary on Saturday if I remember

Brett Miller has done some 59 and 48 degree versions. There is a 59* version on Facebook, as Shiloh mentioned, that made lots of steam.