Okay, I am not an expert, but I thought I did everything right when I bought a 1966 thunderbird with all matching VIN numbers (6y81q138432). The car had a blown head gasket so I took the heads in for re-working. The machinist told me they were 390 heads. That started a sinking feeling that something was wrong. So upon looking at the engine cast: "C6ME-", I called him with that and he told me that in looking that up the book says the cast code was for "all Ford Engines EXCEPT a 428" Is there anyone who would agree with this machinist? I am very discouraged as I paid a higher price for the car for a Q code engine. Many Thanks.