You could use a starter housing cut from another bell housing (the CVH B5 gearbox for example) then using the gearbox sandwich plate on the CVH use this to line the housing up on the MTX box and weld it in place.

The only reason why I mention this is because it was the way I used the ib5 box in the Ka with the frst engine. The Ka starter is on the back and the CVH needed it on the front, this was the quickest and easiest way of get the starter in the right place without messing about with taking the box apart.

What I don't know is if you could then use the CVH flywheel and suitable clutch and if the input shaft on the MTX box would fit the clutch?