I see what you're saying, but it would be far easier moving the EASA to FAA way (barring right to work and immigration arguments). You wouldn't need to line the pockets of one of the few ATOs that you MUST use to do your compulsory study, in your spare time, then take 3 weeks off work to travel half way across the country to attend mandatory groundschool
You only have to complete theoretical knowledge training as required then pass the theoretical knowlege exams - that's the same requirement were you converting EASA > FAA (14 CFR 61.123(c)). See CAP 804, Section 4, Part Q, Subpart 2, page 3, para 3.2.1:
ICAO CPL (A) holder to Part-FCL CPL(A)
Undertake Part-FCL CPL (A) or ATPL (A) theoretical knowledge instruction as determined by the Head of Training of an approved training provider and pass all Part-FCL theoretical knowledge examinations at CPL level.
...
ifitaint..