Do you have the steady rests for the back to support handles and shafts?
Is this the toolbox model or which model, a picture of the setup you have will be helpful.
I made a head stock with dual chucks, and one with duel ER40 collets. The headstock I use for repairs is just a single end ER40 and I use steadies in front, like for tip replacement or a home made side Vee block rest. I use a rear steady for joint facing etc. For the rear steady, I use either a single bearing steady rest and have made a bunch of tapered ID sleeves, or I use the steady rest with a 4 jaw chuck or the 3 or 4 jaw self centering ones. I have lots to choose from, just depends what is available.
Neil