Check Breeze for new pumps and tanks
http://www.breezeautomotive.com/
2 fuel pumps sounds a little odd you might call Vince the old owner and ask him about that, he may or maynot know that story. Baffle loose I don't think thats normal mine was not loose just had it apart a few weeks back. Not sure loose would hurt anything really but I think the Baffle is for anti-slosh in the tank. Was your fuel gauge working when you pulled the tank ?, nows the time to service that too while the tank is out. Finding a good used late model Mustang gas tank if you want to replace it should not be too hard. Check the wrecking yards on south Sunrise. The FFR tank is the only one I've seen that would bolt right in. Some sort of fuel cell is another option but mods will probably be needed.