Hmmmm, well, it has got Cleveland like valve covers and I'd bet those pipes are 2" which would make it more of a "Boss" configuration, if it is truly a "small block," but why?
Looks like a jet boat project perhaps, but 770 HP? Could it be a Nascar lump?
I'll give it a real wild stab in the dark and suggest you might have to hit 5,000 rpm just to get away from the lights with that in the back :laugh: