292 Engine Code

[Seanext]

I have searched every site I can find and I am still unclear how to decode these numbers. This engine is in a 71 K10. I am now pretty sure it is not the original engine. This is what I have so far:

Casting number
3921970 66-76 292

con 2
conveyor 2

J 12 7
Oct 12th ?

Distributor pad
F1117UA
Flint plant ???? ??
Nov 17

The two date codes do no match in the casting date and the date stamped on the pad.

Any help would be greatly appreciated. Getting ready to rebuild this engine just want to make sure to order the correct parts.