ron,
I have always used .006" on 261 intake valves, as per the 1954-1960 Shop Manuals (there was no 1961 Truck Shop manual and I cannot find my 1962 manual).
The 261 exhaust valves are set looser than a 235, .018"-.020" (depending on the size of the truck and the year of the Shop Manual or the Owner's Manual).
Tim
