Fox Lake 518 Build, Dyno, and Carb Test

I'm not much on watching plain ol' dyno videos, they aren't very entertaining.  Fox Lake has videos which are pretty cool on a 518 they built and not sure if anyone has seen them.  It's two separate videos that goes into the build, then a dyno, then a carb shootout... very well edited.  Look like iron heads with custom made shaft rockers, too.  No exact specs on the entire engine, but I thought I'd just post it up to share:

Build:  

Dyno and carb shootout:  

why did I see two different heads on the engine,looks like they had efi castings then back to a carb casting(dove,dooe-r,d3's)....? then they dyno w the efi heads...?