Bike looks super clean. Check out my thread as I'm doing the same stuff to my '78...hope to get it as nice as yours. Had to replace lots just to get it back to OEM as it was missing some stuff.
The '77 seat is a better seat though IMO. It's truer to the classic CB look, and it suits taller riders better. My '78 will have a '77 seat in about a day. I also hate the seat rack, but I know I'm probably a minority. To me, it breaks the simplicity of the rear. But then again, I'm sure if mine had it, I'd be skeptical to remove it.
But realistically, I just turned my bike into a '77k. It's only identifiable as a '78 by the frame badge.