well if you have all 200 hours from usa then you can straight away get your licence converted
those previous 50 hrs will still be there in your logbook
just get the page stamped and signed by the cfi of your school
and i also feel that you might have also done all your checks and recency from usa itself then get all certificates done from usa only
so for you, it will be just a normal conversion process as per the statistics you have given to me