I didn't see it mentioned but the seats were a lot different too in addition to the locking mechanism on both the seat and frame. The tank emblems were slightly diff. The 71 was unique in many ways. I would encourage you to find or paint the headlight brackets however. If you do switch the rear chrome bracket, you will need to find the signal fixtures. I have a poly blue 71 as well and now have it in the orig Japanese frame with no vin label, hole in upper triple and weird kick stand. Still looking for the speed limit h/w.
I would say the most noticeable things are the paint scheme, emblems, rear tail light and gauges although many k2s came with the K1 gauges.