Your COPO official production date has the same exact date as my X77 HO Z/28 (07A July 10th) according to my NCRS report. I have a lot of original born with assembly line parts still on the car and many are dated May. My 302 engine assembly date, heads, distributor, alternator, and carb for example are all May. The Muncie and BU rear are June. I think April would not be out of the question as they were about to wind down for the one month shutdown and were using up all available left over inventory. July 11th was the last day of production before the one month shutdown. I hope this helps.

That's not how the body bank worked. All 6 of the lines in the body bank were always feeding the main line. A given car left the bank within minutes, not hours, of arriving.
http://www.camaros.org/assemblyprocess.shtml#chev
"There were usually six lines in the schedule bank - one for RS, one for A/C, one for SS and Z/28, and three for high-volume standard cars, so cars could be scheduled without having situations like three A/C's in a row, three consoles in a row, three RS's in a row, etc., as these had higher work content vs. the standard cars and scheduling two or three of them in a row would over-cycle certain line operations."

April is too far out, IMO. Could happen but most parts are mid to end of May or later.
Your alt was 9E23, right?

Yes it is.

The other option for a date code I found is the 3rd week of June. Would that be too close to build date?

No

Thanks everyone for the help. These are the parts I’m trying to track for the restoration are these

4346 Carburetor
1111499 Distributor - heard these weren’t made pass the 28th of April in 69?
178 / 879 Smog Exhaust Manifolds
CX TH400 - this is proving difficult to locate to say the least
Smog System

Been able to find most of everything but just want to make sure it works with the date codes. Don’t mean to be too much of a newb to all this so I appreciate all the info you guys have shared.