Best way to move/extend wall-mounted outlets when finishing basement?
This is so easy, you'll laugh.  


unfish the cable out of the last segment of conduit
pull the conduit off the wall
use a conduit bender to put a slight S- curve in the conduit,  so it's out from the wall 4.5" more than it was.
put the conduit back on the wall
fish the cable back in. It will still reach! It is still the same length as the conduit. 


Now, the junction box is 4.5" proud of the wall, and 1" or so higher up the wall.   Build your wall, make sure to include a hard point to mount the junction box.