Hi Marty,
i don't think there is a simple way to do this - the map is part of the contents of an article, and the Joomla template you use defines the "screen real estate" that the article can use. I can not see how the map could be bigger than it's container (html/css-wise) - that's just how the Joomla templates work...
The only way i can think of to get around this would be a popup (like a Lightbox/Slimbox for photos), but i wouldn't know how to get the map in there - maybe someone else has an idea?
cheers, Frank