Cast date code question-engine build match cast parts?

[RALLY]

I have a 1972 Chevy Nova SS with a 350 Flint built motor. The engine was built the 27th day of January 1972. I am currently trying to match a correct cast water pump for this engine. The water pump date code is L-21-1, reading December 21st 1971. So this water pump was cast 5 and 1/2 weeks ahead of my engine build of 27th January 72. Is this correct for a numbers matching engine of mine and if it were judged at a car show would this pass the correct time limit for my engine? Any help and input is appreciated.