Mark;
1972 was the first year that the Chevrolet started the engine I.D. in the VIN number. The LT-1 engine option used an "L" designation in the 5 digit. Tank sticker or other documentation is nice. If the car has the original engine and the engine pad stamps are still there you should find a "CKY, CRT, or CKZ". The last code is for a LT-1/ZR-1. No automatic tranny was used/available with the LT-1. You should find a 6500 red line tach. A Holley Carb (R6239A), aluminum intake, open style air cleaner, and big block style hood w/decals. Seems the most common driveline combo was the M-21 4-speed w/3.70 rear end. Distributor number was unique; #: 1112101.
Hope this helps a little. Good luck!
Steve