Deepsea69ers

I just purchased a 79 M20K and on the transit back to KGTU ran into a few squawks. I am limited on panel space so need a KY 197 direct fit replacement. Has anyone replaced this slim radio with a more modern radio that doesn't require a ton of other mods? Looking at the Garmin GTR 200 but I am not sure other than size fit if this would be the right radio to limit my troubles. Any experience is helpful!