The bulb package should have chart on it. what shutter speed is that guide number for? Yes, no need to waste blue bulbs on b&w film.
Also does your shutter have an M sync position. If only X you have to use slow shutter speeds as it take approx 20 milliseconds for the bulb to reach full brightness. Also if the bulbs are labelled FP, they have a much longer burn time for the old slow transit speeds of focal plane shutters on press cameras.
Make sure you are using a Graflex synchronizer to trip the solenoid. That will provide the proper delay between bulb flash and shutter release. Your shutter is X synch so using the internal flash circuit will not work for bulbs.
Ok, so you are going to get a mix of ambient and flash. The ambient light should be a relatively steady source. The flash bulb will be a known amount of light. You have two options to change the balance of ambient to flash. First you can use some sort of filter over the flash lamp and reflector. Many years ago the photographer may have used something like a linen handkerchief to reduce and soften the flash. The second way to reduce the flash output was to move the flash bulb farther away from the subject. There are auxiliary flash units for this purpose. You need to run a cord from the synchronizer to the "side" flash unit.
"She's always out making pictures, She's always out making scenes.
She's always out the window, When it comes to making Dreams.
It's all mixed up, It's all mixed up, It's all mixed up."
I suggest you meter the ambient light exposure then add one thickness of clean white cotton handkerchief fastened with a rubber band over the flash reflector will reduce the bulbs output by one stop, or two thickness's two stops.