Great video!
I like your selection of fixes, except the necessity of the change of the UHF modulator for a mini-Din connector. What if you need separate Syncs some day?.
I personally hate the Spanish RGB cable from Retrocables, a very bad and expensive for the money product, and this is said to you by an Spaniard. Why not try making the cable yourself? Good quality EDGE connectors are still available in China, and you only need to have good hands(evident on your video) and tailor it. On the other side, there is an Hungarian maker that can make you one cheaper and better finished cable(ask
Judge)
About the audio-out jack base.... I am sorry to say you that it has been a waste of time and one more scar on your loved EP. For two reasons: first, you already had a stereo audio out jack on the TAPE Save jack, and second, with the correct level, because the audio of the RGB connector is excessively low and you will always need the volume of your Tv pumped-up to the MAX....
Another fix that you will need soon or later is to disable the internal speaker.....
