The +5 crown race is available right from King for $12. http://chrisking.com/parts/baseplates
I'd install the fork and see if it clears first. If it does, don't worry about it. Obviously, if it doesn't, get a +5 race. The reason this happened is because the downtube on 29'ers was a bit steeper angle than a 26" frame, causing contact from some forks, esp. those with "stanchion top" adjusters (like the Rock Shox U-Turn). Also, the 29'er frames at the smaller size of the spectrum had a bigger issue with this because of shorter front end length, causing an even steeper downtube. A lot of both frame and fork manufacturers have addressed this and if it is all new equipment, it might not be an issue.