Rupp rifles used Germanic locks. A Siler with the tail slightly shortened, and the tail dropped just slightly, with a small "teat" filed on the tail. The locks are also set way ABOVE center on the barrel flat, to keep,that wrist flat and slender.
The KRA makes an invaluable CD of Lehigh Valley rifles that any builder of Lehighs just can't live with out.
I'd suggest, there are MANY more details that are going to be questions before you finish this gun. You'll do yourself a big favor, by getting this CD before you go much further.
But first..... Order a Chambers Siler!!!
If you want to see some great contemporary Rupp rifles that are done right ......... Go to Allen Martins site.