I’m not sure about this machine but on some drill presses and other small mills I have seen the front cone pulley fits on a short hollow tapered spindle that runs in a pair of ball bearings that are in a housing attached to the top of the machine .
The bore of the spindle has internal splines of carries one or more keys .
The splines or keyways of the main quill spindle slides up and down through and is driven the top spindle .
The pulley has a tapered bore to fit the upper spindle and is some times held in place by a special nut in a counter bore on top of the spindle that may need a special pin wrench or spanner to remove it .
It may be a bit tricky to pull the pulley from the taper if it has been on for a long time.
I would suggest NOT using conventional 2 or 3 legged puller with much force over the outside of the grooves pulley to remove the pulley from the taper since you can damage the pulley very easily but rather something that threads in place in the bore of the retaining nut if there is one .
You may have to make up a special puller along the lines used to remove the grinding wheel and hub from a surface grinder similar to the one shown here.
https://www.practicalmachinist.com/...urface-grinder-no-2-startup-woes-dscf0020.jpg
found in a Google image search.
P.S. I can't get any pictures at the moment but my Matheys shown at the bottom of the page on Tony's site,
Matheys Semi Jig Borers & Millers has the front pulley held on to a taper with a special nut in the centre as described above.
You can't see the nut in the pictures but you can see the socket cap screws on the retainer for the short upper spindle bearings below the pulley that may be similar to the ring you removed on yours .
Regards,
Jim