The 500hrs for European jobs is the more recent OGP requirement for copilots, not strictly licensing. It's HELICOPTER time, btw.
I'd sell one kidney for your 'rights of abode' all over the place including Brazil, haha. Almost.
If you want to fly twin helicopters insted of F/W and save on starting out, with generous experience credit, I'd go the FAA route and THEN convert to European ratings if necessary, as you'd have reduced CPL training requirements (not so much with ATPL theory, but flying/expensive bits wise) and IR training, although if you convert to European IR(A), the cost saving is negligible with Euro IR(A) to IR(H), compared to FAA IR(H) to Euro IR(H). As said, if you do fw ATPL, it's reduced theory for (H) and can use the IR(A) for credit. Anyway, EASA regs don't stipulate minimum conversion training, but you may come across some 'past practice' ie the 10hrs fw to heli IR with European licenses.
Not to mention, if you don't have GA/instructing/scenics job flying helicopters in USA or Europe, there seems to be OK job market for R44 charters in Brasil. At least that's the impression I got from past reading, before people get to 500hrs rotary for the twin offshore jobs.