Harvey Pohn, one of the original US Geological Survey lunar mappers in the 1960s, had opportunities to observe the Moon with the Mt Wilson 60" telescope. He noted the times when crater walls cast thin shadows while other nearby craters were shadow-free. He published a short list of 19 craters with steep slopes, and stressed that since shadows were still visible, the slopes were actually steeper than he measured. These slopes have been entered in the-Moon wiki and can be found by searching on "Pohn".
H.A. Pohn, 1963. New measurements of steep lunar slopes. Publications of the Astronomical Society of the Pacific v75, p 183-5.