WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
Building, troubleshooting and testing of these amplifiers should only be
performed by someone who is thoroughly familiar with
the safety precautions around high voltages.
I am pretty much doomed with that hole until I find another faceplate...as I think a toggle or any other stuff would just ruin the beautiful look (IMHO).
I too like it better like this than the original color. Very easy, I used a Tremclad black mat spray can. 3-4 thin layers did it.
As far as the chassis. Once sanded, if you want to bring it to mirror like condition, just use some green ScotchBride and dip them in a bowl containing warm water AND liquid soap (the one for the dishes) and bingo!!
I got that trick from a professional machinist who does stuff for audio manufacturers in my area.
Finally, the female speaker connectors are NOT standoffs. I bought them on Ebay. They are made especially for vintages if memory serves me well.