A single 3-500z input impedance is roughly 100 ohms but there is no cookbook approach to this without understanding. Two tubes in parallel should present approx. 50 ohms. First try 50 ohms in and 50 ohms out and feed with fairly low level. Or feed network at a watt or so from your transmitter into a 50 ohm load. You will need loaded fully loaded currents and voltages to make it optimum.
But read stuff like this
http://www.w8ji.com/tuned_input_circuit.htm to understand what is going on.
You are dealing with a dynamic system so the Heath designer in the reference had some very germain experience