Who would you let rebuild your Holley carb?

From you symptoms, it is hard to say if it is lean or rich... It looks like the choke butterfly is snapping closed when cold and not running; is this correct? Is the choke butterfly popping open a bit when the engine fires? It should open up a bit as airflow gets established; this is the choke pull off function. If not, try turning the choke adjustment (the round black thing on the passenger side) 1/8 to 1/4 turn CW to lighten up the choke action a bit.

With cold weather, it may be a bit hard to get the choke and fist idle set right, especially with a strong cam, so it may be easier to just keep lightly pumping the throttle and holding yourself at a fast idle setting to get it warmed up, and then set the throttle higher for break-in. For anyone not used not used to carbs (and you may indeed be), this is a learned technique.

Also, look down the secondary throat and see if the back edge of the secondary throttle plates have just a tiny crack between the rear edge and the throat.