I am finding some more famous golfers that play(ed) opposite their natural inclination on the internet. Note the Hogan comment: He claims to have regretted his left-to-right conversion! In the interest of full disclosure: Other web-sites claim that Hogan denied ever being a leftie, calling this a rumor.

Jerry Barber - Converted to right-handedness in childhood.
Ben Hogan - Played right-handed, but was actually left-handed. When Hogan began his career, he was told that he should golf right-handed, with his left hand leading the swing; supposedly, this would enable him to benefit from the greater strength in his leading hand. If this were true, then all right-handed golfers should play left-handed! In his later years, Hogan remarked that his greatest regret about his career was that he had allowed himself to be talked into playing right-handed.
Bobby Jones- Played right handed, but was actually left handed.
Phil Mickelson - Plays left-handed, but is actually right-handed
Johnny Miller - Left-handed, but played right-handed.
Nick Price - Left-handed, but plays right-handed
Mike Weir - Plays left-handed, but is actually right-handed.

Other web-sites also list Sergio Garcia, Sam Snead, and Moe Norman as left-to-right converts.