Fill adaptor should be straightforward as this was an off-the-shelf item, not made by Mike AFAIK. If no one has done so by the evening I will post a picture for you. I think it's the same as the Rapid buddy bottle adaptor but do wait for someone to confirm.
Magazine will be tricky but you might get lucky.
You probably won't have any trouble selling the rifle should you wish to do so. I'm sure there will be a Skan enthusiast or completist willing to take it off your hands who already has magazines.

If you can get it running and get a mag, they are superb little rifles.