Most likely it (the "6") is not indicating "1956".
The format for
Engine Serial numbers in 1956 was different.
Regarding the "A" in : FI008A
The A indicates a car engine (engine in a car with a standard transmission).
The block most likely had hydraulic lifters (but, it could have been used with mechanical lifters).
My bet, now, is that you have a factory replacement engine that was cast after 235s were regular equipment, perhaps cast in 1966 (maybe in 1976, if GM was still making replacement 235 blocks in 1976).
Maybe someone else has other explanations/postulations/speculations?
Do not get rid of that block. Even if it is bad, someone might want want it for its "peculiarity value".
