I am rebuilding the 428 pi in my '68 GT500 and before I get too involved I am trying to determine without any doubt that my engine is original or at least correct for my car. I believe mine is just before vin stamping came out. My car is a January of '68 build car and the casting on the block reads: C7ME-A. Every site I look on I come up with a different out comenfrom it being a December 67 block designated for a Shelby to it being a mercury block. Any help would be greatly appreciated.