The "T0816HC" means the engine was built at the Tonawanda, New York engine plant on August 16th; the year has to be determined from the casting date. In any event, it's not a Corvette engine, as all St. Louis small-block engines were built at Flint Engine, which had an "F" prefix instead of the Tonawanda "T".
The A.O. Smith bodies were numbered in separate sequences between coupes and convertibles (just as St. Louis-built bodies were), so two A.O. Smith cars, one a coupe and one a convertible, built one after the other, would have body numbers far apart, depending on what the "mix" had been up to that point between the two body styles. The "body number" on the trim tag has no direct relationship to the car's VIN number.
Lucy, your engine will have two codes stamped on a machined pad on the block just in front of the passenger side cylinder head; one will be a seven-digit engine plant code, starting with "F", and there will be another seven-digit number that starts with a "4", followed by the last six digits of your car's VIN number, which is stamped on the small stainless steel VIN plate underneath the glove box. If your engine has block casting #3858180, it's not the original engine - all '64 Corvette small-blocks used casting #3782870.
