Marty,
I agree with Ger -- go ahead and purchase larger motors and higher lead screws now. I have 300 oz-in motors on my machine, and sometimes wish I had something a little larger. With the Geckos, you've already spent most of what you need for a higher performance system. Also, the higher lead screws will let you get more speed with very little hit in force due to their higher efficiency (and the lower speed you can run your steppers at). Since these drive the type of nuts you need, I would say the screws are an even higher priority than the motors, especially since motors are easy to swap later.
Ahren
www.cncrouterparts.com