All of the good ones I’ve seen measure 6 11/16" and yes, it’s tight in there so 6 13/16" will be too long.
I use to press them back to size and braze them up but now I’m thinking they expand doing their job when the prop hits a log or something hard so just because they are stretched doesn’t mean the spring is broken. They can be pressed or mounted in a vice and pounded back to size. I’ve done several this way and they are working just fine. 😀
