Hello pace.
I recently got my FAA CPL/IR, and had a look if I could work out in the states as a CFI too as a limey citizen. I asked about working on a J1 visa that a friend of mine did in South Carolina, but the school e-mailed:
"CAN HAVE NO HIGHER THAN A PPL AND NO MORE THAN 49.9 HOURS LOGGED SINCE RECEIVING HIS PPL. HE COULD ONLY BE SPONSORED FOR AN M-1 BUT WOULD HAVE TO RETURN TO THE UK AFTER TRAINING AND WOULD NOT BE ABLE TO WORK IN THE US
WHICH WOULD PROBABLY NOT BE IN HIS BEST INTEREST."
So, unless your present school sponsors for the J1 or you've got a green card I think you're out of luck.
"Have you seen this boy?"