This points up the weakness and strength of these empirical methods. They only do a fair job of predicting actual numbers. Their strength is comparing similar airfoils. So if you have a good set of data on an airfoil similar to the one you want some numbers for, you can estimate the numbers of...
Actually not quite the same. NACA added the camber to the symmetric airfoil perpendicular to the camber line. Riblett just added the camber to the y coordinate of the symmetric section. So Riblett's airfoils have somewhat more camber than the equivalent NACA sections.
Riblett did publish cusp as well as non-cusp airfoils (GA Airfoils book).
The cusp is the effect of aft loading of the airfoil. Aft loading gives higher lift coefficients, but with higher negative pitching moments.
The NACA airfoils (Theory of Wing Sections book) provide a great set of airfoils...
What I was interested in for specs:
design lift coefficient and Reynolds number at cruise, climb;
design thickness, zero lift pitching moment.
If you have a plot of the lift vs drag at the cruise Reynolds number that would be good too.