Jason clarifies what I was suggesting.
Make an adaptor to go onto the spindle, (It can stay there ) that wil accept the chuck(s ) that you want to fit.
This is the easier way. The adaptor effectgively changes the spindle nose to one that suits the chuck(s ) you wish to use.
Take look at the latest post in My Albums, to see one that I made to fit 7 Series Myford thread chucks to a Myford ML4.
For another lathe, lacking a specific backplate, a backplate was modified and fitted to that particular chuck.
The lathe then had a choice of the original 3 jaw chuck, or a modern 80mm 4 jaw, (intended for a mini lathe ), but now fitting a 3/4 x 10 Whit form spindle.
In both cases the original spindle and its internal taper are preserved..
Having made and fitted the adaptor to the spindle, leave it place and mount the backplate for any other chuck on it to face it and turn the OD and register before fitting to the chuck.
Howard