@etheling Hi, finished the same project...
I have spent many hours trying to get the overlay and Atari ST screen to line up. Could you Please post all the config files? I say config because Im doing mine on a Raspberry Pi 3... Tanx

Way cool @etheling !! I've been thinking about doing this same exact thing. I've been perusing for Atari 2600s that are non-functioning because I can't bring myself to 'descrate' a working one. LOL. Doesn't seem like anyone held on to a non-functioning unit. (or at least I can't find one)

@Dochartaigh good points all. I hadn't really considered a lot of that so thanks for the insight (well, in$ight :-D).