I know that here are some vintage owners around. If you have the original bands with your watches you can be happy (like me). I made some experiments by fitting some other bands to check the different look. Here are the results:
1) Sub 300 on a soft grey-brown leather strap. Very comfortable to wear
2) Sub 300T on a „Bond-Style“-Nato-Strap (Nylon, black/grey). Very army looking.
3+4) Sub 300T on an Oyster-Style bracelet with curved end-links. Offering more stability than the original one.
5) Sub 300T on an original Doxa-leatherstrap (not longer available)