Slideshow default sizing in Joomla

Is there a way to change the default slideshow size (320x320) to a larger size (800x800)?

My problem is that with G2 embedded in Joomla the size of the frame appears to default to a small size and one is forced to scroll the slideshow image when selecting a larger slideshow size. See http://www.tripoliidaho.org and go to the photo gallery, pick an album and try the slideshow (not the full-page Java app - I added that for viewing in the meantime until I can solve this issue).

Thanks!