According to the circuit, the LDR must have a value of >75K to ENABLE, not to DISABLE. This circuit is designed to have the headlight turn ON in the dark, not turn OFF. It all depends on how the LDR is connected to the circuit whether it turns on when the resistance is high or off when it's high. For example, street lights are connected in a way that turns on the circuit when the resistance is high (in the dark), whereas certain light-activated alarms turn on when the resistance becomes low (in the light). I believe at the moment you have it backwards. Chances are if you connected a LOW resistance resistor in place of the LDR the LED would turn off. I don't think this is the right circuit for your project. You want one more like this one:
Depending on the load you plan to use with this circuit, I suggest you use a transistor that can handle a fair amount of current (perhaps a 2N3055). I'm a little confused about the last line of your post saying "Ideally I would like to have the circuit work in daylight and to just stay high at dark." Are you saying that you want it to stay on all the time?
Anyway, I hope this new circuit helps, and good luck!
Der Strom