The Z-axis is doing my head in

My idea of welding it together is doomed to failure I think - the original bridgeport quill stop is porous and soaked in oil, any attempt to weld it simply creates a pool of oil and crap welds. I managed to tack it up but that only got me to my next headache....

Alignment is being a bitch - I can't seem to find a position where all the parts just play nicely, there is a fair amount of stress and strain between the screw and the quill, it can be moved up and down by hand but I'm not happy with it from an engineering point of view.

Not sure how to sort this at the moment, a right PITA.

I might just bolt the two parts together and see how it goes, that will allow me to shim things here and there for alignment, seeing the one from Komatias above being held by an M8 screw makes me think this might work.