I would stretch a string line that's spaced away from the wall evenly the length of the line of copy off of two nails,....I then would adjust the pads by cutting the studs so that the letters match up to the string before putting any adhesive on the pads,..there shouldn't be that many variables with split block so you can precut two or three different length studs to do this beforehand,..the pads are mounted to studs which are threaded into the back of each letter,..once the letters line up with the string line add adhesive and stickem to he wall,...its a royal pita so charge the customer accordingly as its going to some extra time to do it right