The eighth digit on your Vin number should either be an L or an M in 1982 for an L motor with air-conditioning It should be 14006712 it’s a seven blade fan .In 1982 if you have an M motor the blade number is 14009080. That is a five blade fan 19 1/2 inch diameter. This is right from my GM parts...
Are you running stock exhaust ? If so check to see if the heat riser os stuck closed on the right exhaust manifold . I had the same issue with a 78 c20 would overheat at traffic lights cruising down the road it would go back to 180 . Everything on my truck was stock , i also went thru changing...