I found that when I followed the racker's calculator for my 10 gallon batch, I used 22 pounds of grain and 1.25 quarts per pound the calculator said it would take 8.64 gallons of space. Well, it was filled right to the top. Not an inch of space to spare in my 10 gallon Gott. The calculator can't take the space under the false bottom into account. If you have a manifold, your volume will be different than with a false bottom.
My MLT is different, of course, but I think that you will not be able to fit the 1.25 quarts/pound in your MLT if the calculator says you need 49.44 quarts of space.