Some info for you here as I converted my JAA ATPL to an FAA ATPL 2 years ago.
Whilst I was completing a type rating in Houston Texas, I thought it was a good opportunity to convert at the same time.
I went to a ATP Academy( FAA CPL/ATPL Test centre) which offered the ground school. The website is
www.atpflightschool.com
I started at 8am and sat in front of a computer going through 1500 questions of which they will ask 75 or 85 questions. They will give you all the formulae's you need for the mass and balance questions etc etc so you dont get surprised.
I went through the questions for about 4-5 hours and then when you feel ready they will set up the pc based exam which is exactly as the practice questions.
I think the exam was about 3 hours but if you are able to go through all the questions and remember them then it should not take so long. Some differences from JAA but nothing massive. I had a few on being current, holding alts overhead military and civil airfields, runway and taxi markings and at least 8 on mass and balance on loading palats.
After passing that one theory ground exam, I completed the flight test (LST) in the sim when I did my check ride and the rest was just paperwork.
A month later in the post arrived my FAA ATPL licence card.
So basically:
I x theory exam
1 x check ride in sim or flight test
1 x medical but they accepted my JAA class 1 so was no need
Like I said this was 2 years ago so maybe some things have changed but get hold of ATP if you in the states or i think there is a company called GlennAir here in the UK that also do the conversion.
www.glennair.co.uk.
Hope this helps and good luck
