Have a look at AngloAmerican in Sandiego. Good school, amazing scenery and great flying all very reasonably priced to. The conversion of your license is a doddle. 2 forms, £35, maybe 4-5 weeks waiting and a quick interview in the USA with the FAA, very simple and well worth doing.
I was out there October last year for 4 weeks and had 2 days I couldn't fly due to weather. Accomodation with the school is good and clean.
Well worth a look.