If you intend to register it in the US you will have to first deregister it in Brazil, and then apply for Registration in the US. After that is accomplished you will have to apply for an Airworthiness Certification for Amateur-built aircraft, so make sure you have documents/build logs to prove that it was 51% built by amateurs. A local DAR in the area in which you intend to move in the US should be able to help you.
Vic