Vol423,
As we "mature" we all seem to remember things a little differently than they may have been at another time. If I stop on the staircase, I sometimes forget if I was going up or down! I really think you do have a Penn rifle. As to previously being a flint, I don't know, it could have been. The reason I said "may be a replacement" is the fit in the mortice and the shape of the plate against the mortice. Nice rifle all the same. Have someone look at it before you do much, if any, restoration. The damage and condition is honest and sometimes things are better left alone. If you decide to do some restoration, there are a number of well qualified folks around, including some on this site.
Mark