The RV-4, -6, -7, and -8 all share the same airfoil and chord. Wing tips are interchangeable.
As a matter of fact, I just installed a set of -7 tips onto my -6.
I tried buying a -4 in Idaho that had -7 wingtips on it. It sold so fast I couldn't even get to see it. The -7 tips look really, really nice on that airplane.
[edit] here's the photo I saved from Barnstormers.
I decided after seeing this plane that if I bought a -4 I would change the wingtips as a winter project, it just looks right to me.
