Hey, just finished an X1 conversion a few weeks back for running aluminum widgets and junk. Actually getting around 0.002" repeatability from the original acme leadscrews. Have you had any luck finding a kit yet? If not, here's some advice:
*Don't cheap out on the controller/driver. I bought a driver with max 2 amps per channel, allowing me a maximum motor rating of around 280oz in (I think it was around there). Even with a 2:1 belt reduction, I run into issues with insufficient torque on the Y axis; reduction also makes things slow.
*Drive from the dovetail, not the quill (Z axis). Locking the quill will provide more rigidity during cuts. Keep the dovetail tighter to eliminate any tilting, and use something more powerful to drive it.
*Gut the plastic spindle gears, and go for a belted setup.
*Consider buying extended axes, I think that's my next move... Or buy a bigger/better machine to base your conversion on. ::cough::
It's a fun little machine, but extremely limited .