I would vote with the hub date for the time being. It looks about right, where are the rear fender mounts above or behind the drop outs? IIRC Hercules was taken over by the same conglomerate that owned Raleigh in 1954. The head badge may give some insight. I have a 19?? Hercules Skyliner, it has the older style round badge. The shifters are still fairly easy to get. I bought a couple off of ebay not to long back. You really need the stock shifter to make it shift properly. Many of the older cycle stores may still have a few instock, you are also going to need the fulcrum point, pulley and a new cable from the looks of it. Chain is a standard 1/8", saddle is going to be your choice my Raleighs all have Brooks B67's on them.
Aaron