Are you sure about that? I believe Singapore is the only airline to purchase the ULR variant and they only put 161 seats on the ULR (versus our 306) and they de-activate the fwd cargo door. That isn't a "normal" interior.

The ULR takes advantage of unused space in the wings to gain an extra 3,000+ gallons per side through additional piping and venting. Our 350s routinely depart with the ability to onload another 40,000 lbs in fuel but can't because of the Max GW for TO limit. The last one delivered (3513) bumped up the Max GW for TO about 11,000 lbs but that still leaves the ability to upload another 30,000 lbs +/- which makes the ULR a non-issue (at least for Delta).