Square Port BBC Heads Value

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I sold a 69 Camaro 396 Engine and took the other "Running But smoking" Engine as Partial payment.(Nitrous Abuse) It is a 71 402 Bottom end , But it has Date code A 17 6 with Cast #3873858 What I saw on a web site lists them as 1966-67 396 or 427 109cc Closed Chamber Rectangular Port heads. My Neighbor wants them and I am curious what a Fair price for them is so I can give him a Good deal (Better than the Going Rate, but not give them away)