i did recently the same (even if i now doing an EMC2 update)
i retrofitted an new Drehmaschinen und Frsmaschinen Hersteller - Klippfeld Turning lathe which also has an Mill head. Thats why i bought it with special Linear gear for the Toolhead.
I am an it specialist and know electronic quite well (do some micocontroller stuff so i personally think when you want to do it easy use the standard parallel ports and if you have to put 2 or 3 of the parallel cards in there.
I searched long but finnaly i found a controller called tripple beast and verry strong steppers ( Benezan Electronics) i dont have the ballscrew so i have to fight backslash.
i found out the hardest stuff was to get an good CAM Programm for what i have to "lathe" (for milling i have an heiz Portal mill and use different software)
my next step is to build an "Handwheel" which i want to use arduino base like
sansbury95's Channel - YouTube so i can then use the lathe and mill as it was on hand or at gcode .
And then my winter project is doing an Turret. Where i bought already the plans but i am not happy with the air compressing stuff and the way it works.
so i think i will do an second arduino based turret. i want to use the design i bought for the shaft and tool holding plate the rest i will do it controller based. my idea is to also use it for manual mills. where you press button tool x and it jumps to tool x or center drill and so on.
And the reason i want to use arduino based stuff because the software support is cool and no parallel board i only need an usb board for it.
so thats my 5 cents