I can reiterate what shake said. I have over 25 years in Manufacturing Engineering in numerous industries. It's not uncommon for someone to say "Hey we found a two year old pallet of Widgets and we need to use them up or else I'll get my ass chewed for scrapping X amount of dollars". If the parts are still good you use them. You don't care about the date on them.

My observation is that there is an accordion effect with date codes. At the beginning of the year they are pretty close. As you get farther in the year they get father apart, more variability. I think this is even worse in 71.

As for chasing date codes (i do it) I wouldn't worry to much about it. If someone actually questions you on your date codes just ask to see there car then this will happen:

98% of the time they won't have a car or a car of any significance or with most of it's correct parts

1.9999% of the time their car is just as varied as your car

0.0001% of the time you will have met an imaginary character because this guy doesn't really exist.

Enjoy your car and try get as close a date as you can but don't sweat it.