Go here to the IDENTIFICATION section... it opens in Acrobat Reader... and scroll down to page 00-3.
It will give you what to look for on the VUN tags and what they mean.
http://xwebforums.com/wiki/index.php?title=WorkshopManuals
If registering the car, you may wanna copy the manual to show the Inspector that the numbering (missing the "8" had to be a typo... as it should be there like on the car and in the manual.
(My car was rejected and I had to do it all over again because the Inspector dropped on of the "1s" when he filled out the form! In CA the car drops off the computer after 7 years whether or not its been registered as Non-Op and it hasta be inspected all over again...)
I found this chart here:
http://x19gr.50webs.com/tecnical.htm
... and I am unsure of the accuracy.
Note... your VIN's last 6 digits, after the "8" are: 141514.
Reading the chart from the bottom up, and I believe the VIN layout and the PRECEEDING letters and numbers changed after 1979 (which should include some carbed 1980 cars) and then conformed to all international regulations.
Alas... your VIN would make your car a 1982, and not a 1981.
Found this one on an Aussie site...
http://www.x19.com.au/stats.html
Note the 1981 and 1982 VINs on their chart of owners in OZ closely match yours between '81 and '82...
ONE MORE TIME...
BOB Rs list is probably the most accurate and can be substantiated by the actual owners... and it puts your car being built in 1981
http://xwebforums.com/forum/index.php?threads/14509/
HTH... and I still think using an aftermarket A/C system would be simpler, cheaper and easier! I installed one myself in my Vette and it looks "factory" from the cockpit... and even though it was a "bolt in", some mods still needed to be done. Really not much more or less than you would need to do in upgrading and installing used parts for yours. I just behoove you to investigate a bit more before you commit.