The officially specified overall length of the B-58 is 96 feet 9 inches from forward tip of radome (NOT the pitot boom) to upper aft tip of the vertical fin, measured parallel to static ground line. The vertical fin is swept 52° at the leading edge. Overall height is 29 feet 11 inches, measured from upper after tip of the vertical fin perpendicular to static ground line. These measurements come from official Convair documents which I have in front of me as I write this.
The length of Lindberg's 1/64 B-58 fuselage should be 18.14 inches, measured as above. Wingspan should be 10.66 inches tip-to-tip.
It's a good model. I haven't seen one in years, but built plenty of them (and its smaller brother) as a kid. At one point it was released with movable controls connected by wires to a remote control stick. It was to be mounted on a stand so it could be "flown" (early "fly-by-wire" technology!).
For those interested, I'm in the process of creating new scale drawings of the B-58, based on the Convair documents, but it's gonna take a while.
Oh, and if you are interested in the 1/72 Italeri B-58 kit, it's too short, because the kit designers took the overall length to include the nose pitot boom, so it needs to be stretched by about 8%. However, the discrepancy is not just in the fuselage, but distributed throughout the entire length of the model, so all the wing and tail sweep angles are wrong as well.