You will have to cut your core support to put in a 26" radiator . there is absolutely no reason for you to do this . A 22" radiator will cool just as well as a 26" rad if you get the right one . A lot of folks on this forum use champion rads with good results . Cold Case is another source as are several others .
you don't need to cut the support, to install a 26" one, your just not going to get all the potential airflow though it. i used it because i already had it. it's sure not going to cool worse than the 22".