I have been asking the same question regarding my '69 RS since Nov 1991 when I purchased it. Although it has the original Powerglide and rear end, it did not have the original engine in it when I purchased it. The fenders were (and still are) badged 327.
Since I don't have any documentation the assumption by most (including the CRG database) is that my car (Norwood, 01C build) left the factory with a 307 and not a 327.
Shortly after I purchased the car, I was able to track its history back to 1982 and know that in 1982 it was as I purchased it in Nov 1991 - 327 badges and all. (Obviously someone back in the day could have changed the fender badges.)
A few years ago, I tried comparing BDY numbers from the trim tags of various cars against mine to see if there was any sort of a trend. I havenít looked at this information for a while now, but your question reminded me of it. Previous posts to this forum remind us that the body number was assigned at the time of order. Build dates were assigned when the car body actually began to be fabricated.
From the 11 NOR trim tag body numbers that I have collected (not enough for a good statistical average, but a start nonetheless) I have the following:
Build Last Digits of BDY number
From the 1st BDY number (12B build) through the 7th BDY number (last 01B build); if you plot the BDY numbers vs build date, you have a fairly straight line which would seem to indicate, that up to that point, the BDY numbers and build dates were following a logical and sequential progression.
In the above list, the first 01C build is my car. It and the next two 01C built cars have BDY numbers lower than the last 01B built car in the list. From the trend of the 1st seven BDY numbers in the list, you would have expected my car, 220831 to have been an 01A build and the next two 01C cars (225292 and 225431) to have been late 01A or 01B built cars. But all three were delayed, for some reason, to 01C builds.
I know there are a lot of reasons why a carís production could have been delayed including something as mundane as not having the correct color floor mats in stock at the time resulting in the building of the car being delayed until the floor mats were in stock (along with everything else required).
However, what I have also wondered, is could my carís build have been postponed due to waiting on a few additional 327ís to make it to Norwood to finish out production of all 327 / í69 Camaros ordered prior to 1 Jan 1969.
So the question is this Ė is it conceivable / possible that a 1969 Camaro could have been placed on order on Friday, 27 Dec 1968 optioned with a 327? If that happened, the car would have obviously been built, after 1 Jan 1969. I, like you, would like to know when the last Camaro with a 327 was actually built, but that information apparently has been lost to time.