I like it as is, but if you want variants, you could go with a longer, sleeker nose.
Possible variants?
Glass nose for photo reconnaissance or aerial survey work.
Night fighter with German-style radar.
I thought it looked a lot like a mini-XC-120 Packplane, so you could go with a much smaller, sleeker detachable mail pod.
You could even do a really weird one with no center pod, but a cockpit integrated into the wing like the Savoia-Marchetti S.55 family.
The one I'd really like to see, though, is one with floats, like the related SM.87.
Cheers,
Logan