u can just leave it like it is or stick something in there like a some paper towel and wrap it around w/ a tape.

how thicker is ur radiator? if its really thick like more than an inch, then u should go and replace it. if not, then i dont really think it'll matter.

the only difference is that u'll not be able to store as much cool water as you will w/ ur original one, while the car is running.