I'm guessing a bit here but having converted from the UK to the FAA atpl a few years back I'm probably not too far out... Suggest you first contact a reputable training org that offers the GIV type rating.. Unlike the UK it's not common for people to do the FAA ATPL initially...they tend to go for the CPL and then push off to either the right hand seat or single crew part 135 ... only when moving over to the left hand seat of something heavyish do they upgrade to the ATPL and then it's done in combination with the rating... Any decent traing org should be able to line you up with an examiner. You'll have no trouble with the writtens... compared to Europe it's a walk in the park... on sunny day... with Paris Hilton. The oral is unfortunately not with Paris Hilton so you need to know your stuff and the flight test was the toughest I've had anywhere... though i'm told this varies with the examiner... mine was certainly fair but was not going to let anything go by.. a tough 2 1/2 hours...