Beside the working permit...: Many Schools in the US are making big words about the possibility to work as instructor after you invested a huge amount of dollars for the required training into them but finally you will not get what was promised. Specially ME and MEI CFI-hours are rare and if it works ok, you may have to train some student pilots for a PPL.
If you get the visa and work permit, consider very well which training facility will fit your needs and talk to instructors working there.