If you really want a bigger span all you really need to do is inform your saleman that you need to accoplish a certian beam span in the basement at a certian place. As long as its not under costruction yet this should really be no problem. If it is,there are still many ways to get around this if you absolutly have to. 6 1/2' beam span is absolutly worthless! Especially with an engineered gang lam beam?
Good Luck