Hi Randy -
Wow! I think "quite amazing" is an appropriate expression considering the coincidence! I too felt my distributor was original due to the low mileage on the car when I bought it in 1980. I just started checking the "numbers" on the vehicle and when I saw the date code on the distributor, I said "Oh No!" (censored version). That's why I started this post. I wonder how many other early 1968 Z/28s have this distributor number and date code in them? Is there any way to find out? Would Jerry MacNeish know? Please tell me where I can find this 532 CCW number you mention? And, as far as the $2000.00 plus price for this distributor, I paid $1000.00 for the whole car! Of course, that was 27 years ago.
As for the water pump, it would be "quite amazing" all over again if your casting number and date code matched mine! If you start at the end of the lower radiator hose where it is attached to the water pump and go straight toward the water pump hub (bearing) about 3 inches in you will find the casting number on the front side of the water pump. I had to stick a small mirror behind the water pump pulley to read it. The date code is on the other side (driver's side) about 2 inches in from the two bolts that mount the water pump to the block. It's much easier to read. If you can, please check the numbers on your pump and let me know.
Thanks again for posting your info, without it I might have done something stupid with my distributor!