just a heads up
looks to be a 79 with a later 80 -83 speedo, (not original), seat has hinges, frame has the latch for the seat, the tower and rev-counter are from a 79, ........if the wheels are original 79 Special spoke wheels, (19" front/16' rear wheels with alloy rims), they are a one off, one model, one year .....79 Special II.
There are major differences between 79 and 80......charging system, ignition system, and carbs........
The only way to identify the bike is if the Motor and frame no's match and the motor is points, it's a 79SII
If the no's match and the engine has Factory TCI then its an 80G SII.
79 SII and 8oG SII were identical visually. Some differences are mentioned above.