The 450 doesn't really go by the limit of BUS's anymore. youre limited by slots and ports and with 8 DSM 32's and 2 T1 cards, thats it for slots.
You can have up to 300 sets (mixed) and 130 trunks, with the CEC (capacity expansion card) card. You need to use the CEC card if you go over 100 sets.
So the answer to your question is yes you can install that many cards, just dont forget the keycode for the expansion cabinet and the CEC card.