The 8.8 and 8.75 diameter pylon props should be safe to 25500 max (air or ground) and I tend to stay away from N or NN (narrow) props, they seem to slip too much for me.
Betcha that Rossi 61 DF will like the new 8.8 X 9.25 at about 19500 when the pipe is set right.
on sale too:
http://www.pspec.com/details.asp?ProdID=47&category=6