Help me choose steppers for G203V!

[Gnu]

Last night I put an order on three G203V.
Now I need help with what kind of steppers to look for on ebay etc. What kind of specs they should have. Inductance and so on..

This is what I have:
G203V
NSK ballscrew 20mm lead (~4/5 inch)
THK SHS20 (LV on Yaxis, V on Xaxis)

How it's put together:

Concrete! Could need some on the wall behind too

What I want to do:
Milling aluminum as good as it can be done with the setup I have (not including the kress) and perhaps some steel.
For now I have a kress850FME but it'll be upgraded to a new spindle, somthing like 2-3HP and using er16 collets.
Edit: The kress is for routing wood and engraving. Would be nice to engrave like 300IPM but I'm not shure if 30krpm is enought.

Best regards!
//Isak (sweden)

Edit2: Forgot to say that both X and Y have 20mm lead but Z have 4mm lead. AND the weight that the Y-axis should move around (Z-construction) is approx. 10kg. Could be a bit more on X depending on what kind of table I shoose threre.