My conversion is based on a Titan TL180V Minilathe from Titan Machinery, a machine tool importer in Australia. In stock form the lathe has ~400mm between centres, 65mm cross slide travel, 110mm swing over saddle, and 180mm swing over bed.
I'm using Probotix Probostep drivers + 280ozin steppers. I had this 3 axis left over from an upgrade to my CNC router. If I had my time over I'd go with a g540 - it does have two suplus axes, but has many features and easy wiring that make it well worth it. However, I can't fault the service from Probotix. I managed to fry a breakout board by shorting 5V with the USB power plugged in - Probotix sent me a new board, free!, when I emailed them about the problem.
I wanted a conversion that didn't increase the footprint of the lathe (much) but maximised the travel. I wanted an X axis that increased the travel to allow gang tooling.
I'm using 1/2" 6TPI ACME thread. It's very hard to find ACME thread in Australia. Fortunately there is a good bolt supplier close by that can get it. It cost me $50 for enough thread to do the lathe twice over. I made nuts out of plastic.
My X axis uses a spacer plate that is bolted via the old apron mounting holes. On this sits the bearing block. I'm using 2x deep groove ball bearings (from VXB.com) at present, but will move to angular contact bearings eventually.
The bearing block allows the cross slide to pass over the top (just, ~0.5mm clearance) - this means the cross slide travel is only limited by the length of the screw (my screw sticks out the back a fair way). I've drilled holes in the back of the cross slide and mounted the nut there (rather than using the existing nut holes). I get 150mm cross slide travel with the stock cross slide. The real limiting factor is the gibs and gib screws. If I add more gibs screws between the existing I can probably get a little more travel. Eventually I plan to make a new cross slide, probably with T slots for easy gang tooling, which will be longer and have longer travel.
On the front of the spacer bolts the stepper plate. As you can see the stepper mounts to slots - allowing for the belt to be tensioned.
My Z axis just requires two holes drilled and tapped in the end of the lathe bed. The plate bolts there and the rest of the hardware is attached to the plate.