Yeah, that's a 4200's oil filler cap!
Seriously though, yes it appears under all that is a 4200.
WOW, after the vid of the Brazillian drag car with the twin turboed pushrod Chevy (250??) this one should really haul.
Interestingly, it looks as if they have converted to the LS type ignition coils. I remember reading something (I think EFI-DIY) posted about doing that, but I don't recall the why of it(at the moment).
Amazing effort regardless.