The head loss in plumbing is not only determined by the length of pipe but also the pipe diameter, the number/types/size of fittings and the filter type/size. So it isn't just related to the pipe length. You don't say what size (HP) the LX is but all of them would probably produce less than 60 GPM so you are probably ok with that although you might go with the smallest one you can find (1575) to save energy.