Did you look on the Wiki? I don't remember what is on there. If not, I'll have to look around for the full package. If I can't find it, I'll have to rebuild it.
Actually, SCI was designed to have a 4:3 aspect ratio. The reason that on modern monitors the image looks stretched is because the shape of the pixels of a modern monitor are shorter than they were in the old DOS days. This has added scan lines to the monitor, which gives greater resolution. This change occurred with the introduction of VESA/SVGA. However, it made the old games with the same number of scan lines designed for the old monitors unnaturally stretched since the lines are thinner. That is the reason that aspect correction was added to DOSBox.
As to fan games, what aspect is correct, of course will be what ever the graphics were designed for. But the designer should remember that on most monitors that when using full screen, DOSBox will stretch it to 4:3 anyway. Some monitors/graphics card drivers will allow the user to stretch the screen to fill, but not all and most users will not want to bother to set it for individual games. I would have to rewrite the config tool to add aspect correction selection. The one for the run tool is essentially the same one that I had already written for my SCI0 installers for official games.
On a side note, I noticed that you have "scaler= normal1x", which is an invalid entry. That will give you normal2x since DOSBox ignores invalid entries and fall back on its defaults. If you really want to have 1:1 scaling use "scaler= none", but true 300x220 and 300/200 will look like thumbnails these days.