have u tried to see the vin number on the chassis?, maybe you can check it online, also the brake light was custom installed, so the PO wanted to look like that.
Do you have other pictures? Sometimes Ironheads have non-stock parts from other years. It's at least a 75 because it's a left handed shift. It doesn't appear to be from the 80s from the look of the oil tank. It doesn't have a kicker. I'd guess a '77 or '78 but without the VIN I'm guessing.
I'd agree with Baka, late '70s Ironhead by the looks of it. Lots of original parts, but also a lot of new parts. Google VIN decoder for Harley's and you'll have a good idea.