I tried to convert a US ATP to CAA back in 2003.. I bought about $5000 dollars worth of books and started to study.. after about two months of study all day about things that have zero consequence in a cockpit and having sat the fist exam of 14 I think it was going to be.. I realized it was going to take about another 2 years and cost about 150k .. at that time.. the folks at Naples air center who sold me the book work , also let me know that if you had 3000 PIC in a wide body that you could just do the air law exam, and to a conversion check ride in that type.
IT ENDED UP BEING EASIER TO GET THE 3000 WIDEBODY PIC….