Whilst I have never owned, or know anyone who has owned, one, I have always thought the dual purpose machines to be very much less than ideal. The distance between the worktable and the head seems to be too great for one thing. Even the suppliers provide raising blocks to overcome this situation.
I agree with others that using a lathe with a vertical slide is a better option and see you already have these. Does the lathe have a tee slotted cross slide this. is esential?
If you would like to see examples of milling being undertaken on the lathe there are some projects on my website intended for the lathe only workshop, these will give you an idea of what is possible. The index for these is at (bottom right) **LINK**
As was mentioned by Bazyle working sideways can be a bit of a barrier but is not that difficult to accommodate. You could though, once you come to terms with using a vertical slide, consider making a milling head for the lathe such as seen here, a milling machine is not required for its manufacture. **LINK**
The following pages shows it being used for making the horizontal steam engine “Tina” and show that it is capable of some complex work. It is not quite as robust as using the lathes spindle and vertical slide but working that way can be reserved for any heavy duty tasks that surface. **LINK**
Harold Hall