The Lionel steel ties that I have measure 19/32" which is just shy of 5/8". I think the 3/4" screen moldings will need to be trimmed to get them to the right size so they don't stick out like a sore thumb. Easy to do but it will lose one rounded edge so in come the router table to put it back on. I have ordered some of this molding material as well as some from the Kappler site. This is the strip material that is 24 X 1/4 X 1/2" long. I'll try both and see which one I think is the easiest to work with and looks the best.
Since were on the subject of ties, what are you folks using to glue the ties to the rails. I have made a jig that I set the ties into, apply hot glue and then set the track section onto it so all ties are glued at once. Using this system I can do a section every two minutes or so. The problem I have had is the hot glue does not want to stick to the track very well. Just wondering if anyone has come up with an alternative.