Powering up equipment that may be 50 years old or close to it presents hazards. The radio, and especially its power supply contain capacitors that will deteriorate from age alone. If they break down and become shorted inside, this risks collateral damage to other parts of the radio.
There are techniques to do this safely, mostly involving a source of variable AC voltage to power up the radio gradually and a way to limit fault current to a safe level. That way any parts that fail as a short circuit can't scorch the rest of that circuit.
But simply plugging it into the wall outlet and flipping the power on is called a "smoke test". That is, letting out the smoke is easier than putting it back in.
And leaving the smoke in there, is cheaper than letting it out.
This is especially true in the L4B amplifier's power supply. Bigger parts tend to "fall harder" as they say. And if the eight electrolytic filter caps in the L4B's power supply are original, there is very little chance they'll still be okay. That kind of capacitor will frequently be visibly distressed. Bulges in the rubber end plug, or precipitated dusty brown stuff where liquid leaked out are an immediate clue if you see that.
Unless someone updated all four units in the last 20 years, this will be like finding a 1974 'Vette under a tarp in a barn. Would be nice to make it driveable, but the list of issues to address first will be pretty long. Can't just jump in, gas it up and drive a thousand miles.
The manuals for those items should be online somewhere. I recommend you NOT power up the L4B at all. Unless you have a hookup to safely absorb a thousand Watts of RF energy, there is no point to plugging it in at all. And probably a few good reasons NOT to.
73