Not that I would advocate confusing matters by changing the calendar again, but you just move the birthdays same as last time.
From Wikipedia: George Washington (February 22, 1732 [O.S. February 11, 1731] – December 14, 1799)
Notice the year is different. In the British Empire before 1752, March 25th was the first day of the year. March 24, 1751 was the day before March 25, 1752. Then September 2, 1752 was the day before September 14, 1752 The last day of 1752 was December 31, and the calendar has continued how we consider normal ever since.
The British custom of starting the tax year on April 6th survives as a relic of the old calendar (March 25th plus the missing 12 days in 1752).
