Hello!
Well I'm honoured GM mentioned my name! Now I don't know the set you mentioned, but I remember hearing, that the most tanks (and tankers!) in 1920 were from the so called "Haller's blue army" - a unit that General Haller brought with him from France completely equipped by the French. That would mean that you should go for modifying late WWI French tankers and this should do it - unluckily, that would be about it when it comes to my knowledge of that aspect of Polish history.
A little info on what you plan to do would help me reserach it a little better for you.
Good luck with your modelling projects and have a nice day
Paweł