Interesting GM Aluminum Heads Experimental/Prototype Big Block Chevy

[SuperNovaSS]

I recently picked up this pair of factory Big Block Chevy aluminum heads that came out of an estate. One head is casting number 334112 and the other has the 3946074 casting as well as the casting 0334112 as shown. The wife of the gentleman that passed away said her husband called these his "cheater" heads. The look the same as 3946074 heads to me other than the combustion chambers being slightly different. I imagine the combustion chambers were smoothed and has the exhaust unshrouded after they left GM. Has anyone ever seen this casting number before?


Thanks,


Jason