1. my slide comes all the way out over the motor so unless i mount the motor backwards ill never have the room.
2. the original mount is way to small for the new bearings.
I disagree as long as you have good bulk on ether side of the bearing your just not going to apply enough pressure to the bearing collar to get it to deflect, the inside has 200mm of cast iron slide and the outside had 30mm of Ali, im exposing probably less that 1/3 of the bearing which is hardened steel, the motors will give out or the belts will break before there is any significant deflection.
I admit I was a bit startled at first when I saw the way the bearing housing was cut away, but ...
First of all, the driving/cutting forces will be along the axis of the leadscrew, and the amount of metal used seems adequate for the size of the lathe. The inner aluminium support is not fat, but it is backed up by the steel body. The outer aluminium plate is quite fat enough. The holding bolts are large (bigger than the originals?). This is
not a production machine for car axles after all.
Second, the forces due to the drive belt are all downwards, not upwards. The bearing is well supported underneath.
Third, the bearing itself is quite a solid unit and does not look as though it would flex very much :-)
So while it is hardly conventional, I can't see too many reasons why the arrangement would not work.
My 2c
Cheers and Merry Xmas