Help needed, Craftsman wood planer.

[tonyfoale]

I have a small and very old cast iron Craftsman planer which I bought at a yard sale when I lived in the US. Other than a "don't cut you fingers off" notice there is no other info with it. The table is 4 or 5 inches wide and the drum is a touch over 2" diameter with 3 blades. The spindle looks as it it runs in plain bearings but I have not dismantled it yet.
Does anyone know what RPM the spindle should spin at? Failing that, can anyone give me a guide to surface cutting speeds for wood, Google came up with a lot of useless info, many planer users seem to be confused between cutting speed and cutting feed.