I know of three people who will convert one for you.
Carr Precision
WWW.carrprecision.com
BCMA
WWW.BCMAEngines.com
Brillelli
http://www.brillelli.com/page6.html
RC Ignitions
http://www.rcignitions.com/
I purchased my GX35 from the Small Engine Warehouse and had it shipped directly to Scott Ellingson/Mark Brill at Brillelli Engines. They did a great job on the conversion.
Hope this helps.