I speak from experience... I'm a 21 y/o South African - came to the United States in Oct. 2001 to pursue a life long dream of flying here. Done all my training in South Africa including Instructors rating so it would only have been "a license conversion" I thought. I married my American girlfriend in Dec of 2001 and received my greencard in Sept. of 2002. While waiting for the greencard I painstainkenly converted all the licenses. Now I'm a multi & single comm with the FAA CFI and CFII certificates. Aint working out for me. I instruct at a flightschool in Orlando and I'm lucky if I log around 30 hrs per month. My friends in SA are all doing 100 per months as CFI's and some of my friends got turbine positions with around 300 TT. Now my sight is back on SA and I might return to my home country for a flight job. Jobs are VERY scarce here now. Unless you meet the FAA part 135 minimums of 1200 & 1500 TT you're not going to break into a charter operator - unless you're extremely lucky.
I'd be happy to supply info to anyone who wish to do license conversions and other immigration issues pertaining to pilots.
All the best.
<a href="http://www.FlightZone.cc" target="_blank">My website (www.FlightZone.cc)</a>