1976 cb750k head/cam holder questions

I picked up a basket case, cylinders 1/2 cam holder cracked in half, head is shot. I am going to pick up a new head, and matching cam holders. My questions are:

Does it matter what year its off of?
Any changes from model years I need to be aware of?
Does anyone have one they want to sell me?

I'm doing all new valves, guides, springs, cam, etc regardless, so I dont care about all that.

Thanks guys.