I dont even Know, thats how new I am to lathes and lathe work.If the spindle has a standard Morse taper like #2 or #3 then you could get a set of Morse collets and make a drawbar for them.
Otherwise it sounds like a 4 jaw would be best. I like having both.
What type of spindle mount? Do they sell replacement backplates for your machine? The spindle mount pretty much determines your options
as far as aftermarket chucks