To get a FAA IR after completing your Private - you either have to do a Part 141 course or have completed 50 hours Pilot in Command cross country time (FAR 61.65).
If you are looking to hour build then you require 250 hours under Part 61 to gain your FAA CPL (FAR 61.129).
To be honest you might as well simply stick with JAA as it will cost a lot to later convert from FAA to JAA.