You can make pretty much any beer you want with your 7.5 gallon pot but you may have to get creative. Mash in with less water, pull bag and set it into a fermenter bucket and do a dunk sparge to the the right volume. Bring the main amount of wort to a boil until the foam is under control, then add the wort from the sparge. Be aware that this will get you more foam when it comes back to a boil. It may require you to only add part of it right away, then more as the wort boils off some of the liquid. You also may find that you don't get a full 5.5 gallons into the fermenter.