Why no serial number? All RB100s I have seen had numbers in or on them depending on when they were made.
Is this an arch top or flat top model? A 1964 model should have still had the small hoop so it would look like an arch top. Gibson went to the thinner rim in 1965 if my memory is correct. The thin rim would not accomodate the 9 1/2" ring and a larger one was used. I don't see the outline of the ring on the head.
The sunburst resonator looks like one from an earlier period than 1964. By that time the whole back of the resonator was light in color. Sunburst finishes usually are from the 1950's. Usually, the earlier the banjo, the further into the center the black edge goes.
The plating looks like chrome to me. In 1964 the RB100 would have still been nickel plated. They went to chrome plating a year or two later and kept using it until the RB100 was discontinued in 1979 even though RB250s had gone back to nickel plate by then.
The Waverly tailpiece could be correct. Around 1964 was when Gibson completely quit using the Kluson car trunk tailpiece. The Waverly was standard equipment on all Gibson banjos from around 1964 until 1970.
All in all it is a fine looking banjo but some of its features look a little suspicious to me.
They went to the thin rim in 1963. If the banjo has a fiddle cut peghead, and the rim is painted black, then you don` t want it. I have a 62 and added a tonering, and sorry I did. I had Arthur Hatfield turn the rim, and he said it had the same smell as a pre-war. It turned out to be one awesome bluegrass banjo, but wish I had not converted it, if that makes sense.