Barry
If there is room, a bolt to spindle plate type chuck mount can be converted to bayonet ring style. I think the official designation for this type of fitting is DIN 5027 / 55022. Unfortunately my Google Fu this morning isn't up to fiding a drawing.
That style of mount has a ring with keyhole shaped slots aligned with the bolt pattern in spindle plate and chuck between spindle plate and headstock. The bolt holes are enlarged so a plain stud with reduced diameter threaded end can be passed through the spindle plate and the large end of the keyhole slots with the nut still attached. Obviously the other ends of the studs screw into the chuck itself.
When mounting the chuck it is settled onto the register with the studs and nuts passing though the large ends of the key hole slots. The bayonet ring is then turned so the threaded ends now pass through the narrow part of the keyhole slots allowing the nuts to be done up securing the chuck in place.
Obviously the nuts only have to be undone a turn or so, just enough so the plate can be rotated to align the appropriate part of the keyhole slot. Everything stays permanently mounted so no fiddling about with loose nuts, washers and words of power to coax them out of the swarf tray when dropped.
Official DIN versions use a short cone register like camloc and A series chuck mounts but a plain register works well enough.
Major issue with a conversion job is fitting the bayonet ring. The spindle needs to come out to get a one piece ring on. Some years ago in another thread on this site the late, and sorely missed, John Stevenson suggested method(s) of ferreting a two piece ring on and joining the parts in situ.
Maybe making the ring in three sections with the ends joggled to give a significant overlap and gluing together with one of the slightly flexible adhesives might work. If there is room continuous ring could be made bored to go over the spindle plate but slightly thinner than the plate and the sections containing the key hole slots fixed to that.
Clive