1, Ground light right next to terminal block. I copied this guys wiring
...pic... 2, The terminal block is there to tie the parking lights together. Why not just use it?
...my block... I tied two wires into one end trying for a cleaner look.
3, My horn looks like yours. The connections are on the side not the bottom.
...1950 horn pic... I used the bottom terminal for the ground, used the other for power.
A quick test will verify, I dont know if it make a diffrence. I added a relay for the horn.
4. hopefully others can advise
Your wiring looks good, you may want to consider heat shrink for your connections. double check your crimps. The more experienced guys advise adding solder
