Replace the wires before you start messing with the carb.
The arcing you described seeing at night indicates that the cylinders aren't firing, thus it seems to be flooding out. Also, the more they arc the more the insulation breaks down, taking more of the spark energy away from the plugs.
Poor idle can often be a carb/fuel/pump problem, especially if you're flooding out. If you do have a fuel problem, it's either running rich and you can smell the fuel; or it's running lean and you will notice a burnt smell.
Also, before you replace the fuel pressure regulator, you should check the fuel level in the carb. Your holley has a plug in each fuel bowl, when you remove one (after briefly running the engine) a small amount of fuel should come out.
A lot of fuel coming out indicates that your needle/seat can't hold against the fuel pressure coming in, it (needle/seat) has deteriorated and needs replacement, or the float setting needs adjustment (least likely because it ran good before and the setting shouldn't change, of course the float could be leaking and need replacement).
No fuel coming out means float setting, needle/seat, or fuel pressure is the problem (along the line of previous discussion).
Obligatory WARNING - raw fuel spilling from the carb can catch fire causing serious injury or death
, take necessary precautions. Oh and that thing about gasoline and cancer!