RE: size of air filter intake ?
If the foam filter was properly oiled, it should not be so dry as to fall apart. As I mentioned in an earlier post, the frame of the 250 is the intake manifold and the opening is in the side. About the only way to see what you will need, is to disassemble the 'Pod' as you call it, pull the filter and get your measurements. Good luck.
Never tell someone more than they are willing to hear.