Groovymame actually came up with an interlaced mode in the first place, but I don't like interlaced modes. Doesn't feel like arcade to me.
Since I am still a groovymame noob, I just don't want to miss an obvious scaling option that I just don't know.
If there is anybody out there happy with his vertical setup, please share your settings. I will give them a try.
Building a second horizontal cab would be the best way, but I am afraid my wife thinks otherwise.