Ralph
See photo attached.Similar to what you need to know.
Assuming you are using a Nema 23 ?
3/8" thick ally plate, drill and tap 4 holes the same footprint as the stepper motor 4 x fixing holes.
Bore the plate through the same diameter as the motor nose register diameter.
Drill through 2 x holes clearance same dia as the holes used for the taper turning attachment.
Put the cross slide feed screw in the chuck and drill ream a hole for a double connector Male into the C/S and?
male into a "oldham" flexible coupling. that will connect to the stepper motor spindle.
Make 2 x standoffs to the correct length that will connect the stepper and plate and the oldham coupling, to
the existing taper turning threaded holes.
Hope this helps.
--
John