SX2 timing belt vs coupler for X-Y?

I have the Micromark version of the sx2. I plan on keeping the stock screws for X-Y CNC conversion. I do not have a lathe and I do not really want to modify the existing lead screws. When looking at it I am thinking using some T5 timing belts and machining the pulleys to replace the existing handles should be fairly easy and allow more alignment forgiveness. I was thinking 1 to 1 using the smallest size that would have enough material in the hub to machine for my needs.

For mounting I would cut some brackets out of 1/2” aluminum, use the existing bolt holes and just put in longer bolts to accommodate them.

Am I way off on this? Given the small pitch of the existing screw should I try to gear up a bit? I have 270oz Kelling motors on 36V. I have not been able to Google up any info, most searches go back to the spindle belt conversion.

The other question I have is should I add some axial bearings between the pulleys and machine? It seams I have to tighten the existing handles fairly tight to eliminate back lash on the Y axis.

I haven been using the machine stock for a year and so far the X-Y screws have been good enough for my needs. I tend to do cutouts in plastic, aluminum, and steel project boxes along with parts out of aluminum and wood. Another use is cutting openings out of 16-Gauge Steel blank plates such as Middle Atlantic Products - Custom Panel System
Thank you.