BB,I think it all depends on what time the ZG meeting starts(suppose it's the same for Torun too).The last direct train to Poznan from ZG is at 1903hrs.There is a later one at 1924hrs which involves 2 changes back to Poznan.Let's hope that the ZG v Czestochowa starts at 4pm,which should give you a bit of time to get back to the railway station(if that's how you're travelling).
Think it's going to Torun for me(again dependent on what time meeting starts),if that's not possible then it's Wroclaw v Rzeszow.