Wow what a great build. Looks great and your dad will be proud. I just was given a 73 CB350F that was in similar shape and your rebuild is an inspiration for me.
One question, you painted the air and battery box covers with the same paint as the gas tank. I figured they were metal, but mine are plastic for the side covers. Are yours original and metal? Or does the paint that you used work fine for both? I guess I just expect them to be made of metal but maybe they are plastic from the factory. I'm thinking mine might be an aftermarket part if plastic isn't the norm
My side covers are original and plastic. I used the same paint, but prepped them a little differently.
The metal bits (tank, fork cases):
-Sand with 60 grit down to metal with an orbital
-Filler where needed
-Epoxy primer
-High build primer
-Sand with 600 grit
-Paint
-Clear
The plastic pieces
-Sand to plastic with 320 grit by hand
-Adhesion promoter (this was recommended by the mfr of the paint I used to be sprayed before the high build to help adhere to plastic)
-High build primer
-Sand with 600 grit
-Paint
-Clear
I didn't use epoxy on the side covers, but you could. Just follow the recommendations of whoever's paint/primer you use.
Now get to it!