I haven't had any trouble putting lines and backing onto 1494's or 1495's (older ones). I have a 1494 loaded with plenty of backing (want to guess 80 yards) and a Sylk WF5. Also on my 1495 125 yards and WF5 444 peach.
What I do is wind on the line, make a mark on the spool where the line ends. Take the line off. Measure the distance from the line to the spool edge. Make another mark measured from the arbor, fill with backing to that point or just shy, attach line and wind on. Pflueger's line recommendations are for the heaviest lines and least backing.
I have wound on DT 4 silk and DT5 peaches on 1494 (silk) and 1495 (peach) without a space problem.
Pete