I don't recall radial pins going back as far as '91. I had a '91 JW myself that looked very similar to the butt pic of your cue but mine had his standard 5/16-14 Acme thread at the joint. I've seen many in that era but never with a radial pin. Maybe it was new then but that forearm kinda confuses me.
I'll take out the rubber bumper tonight and take a pic of the weight bolt with the year, JW, and serial number. From the looks of the shafts where the pin screws in, ringwork, and radial pin itself, IMO it is all original.
John