The pipes are from a 77 or 78 750, the rear signals, seat and probably other things are aftermarket.
How new are the tires? How are the forks, the swingarm, the steering bearings, the gas tank, the carbs?
When was it last ridden? When was it last inspected?
Ridden this year, inspected this year with the modifications that I can see with no immediate bearing or swingarm work needed would put that bike at $600 to $1200 here in Maine.
If many of those things are questionable, it has not run in a while, and it needs new tires -- this would put the bike in the range of $400 to $800