Travel / Specific question about large baggage on a train from Poznan to Torun [7]

Hi all! First post.

I'm going to be traveling from Poznań to Toruń on a "pospieszny" train on Friday, 5 September, at 1607; the train number is P65104/5. The train originates in Wroclaw and runs all the way to Olsztyn. If you have taken this train: this question is especially for you. :)

I'll have a big, heavy suitcase - probably 100cm x 60 cm x 30 cm. Will there be room for this? I'm in second class. If I'm in a carriage with airplane-style seats, I imagine there will be some space near the doors for luggage, but if I'm in a compartment, I worry that there won't be any room!

I've only been on one other Polish train, a TLK from Warsaw to Toruń, and were I to ride in the same kind of car (second-class compartments) this time, I think the bag would be too large to fit on the racks above the seats.

I can't do the obvious thing and pack two smaller suitcases because I'm actually moving to Toruń for a year from the States, so I won't be able to bring that number of bags with me across the ocean.

I appreciate any ideas you have!

Thanks/Dziękuje!