Despite your map being larger than your iframe, you should still be able to use Google Map's default ability to drag the map around ... sounds like you have this disabled, so I would ensure this works first. See here for example: http://blog.poplabs.com/2009/08/embe...-xhtml-strict/
Using the default iframe method, your iframe should contain the google map at the size of the iframe, thus the need to move within the iframe by dragging it around or using the provided controls. Your map sounds like it is a google map iframe, within an iframe!?