Ultimate Beam Design Needed

I need to know what is the best construction for a beam to hold the maximum weight. The beam will be 33ft long and supported by columns on both ends. The restriction is that the beam must be less than 7" height. I want to know what the maximum load is with less than 3/4" of deflection. I'm open to any type of configuration. What is the capacity of a 6"SQ tube with 5/8" wall thickness? What is the capacity of W6x25 beam with 3/4" or 1" HR bar welded to the outside to form a boxed unit? Thanks for any help!