The single-family mortgage purchase ceiling of Fannie Mae and Freddie Mac, which determines the size of a conforming mortgage in the U.S., is likely to jump by 7 percent or more next year as result of this year’s very robust home price appreciation. According to a new analysis by Inside Mortgage Finance, the so-called conforming loan limit should jump by a hefty $24,360 or more in 2005 based on preliminary survey data collected by the…