Help to ID very Strange 426 Wedge Block

RustyRatRod said
Yeah they called it "Hustle Stuff".

Ahh, yes! But even before that.... im betting this block is maybe 64-5 vintage. And those maxie nascar manifolds were then, or even earlier, as that program was dropped like a hot potato (at least for a while) with the advent of the gen2 hemi.