[NiHaoMike]

How about have the switching regulator operate as both a PFC and a charger? A buck/boost converter can allow it to work for a pack voltage range that overlaps the input peak voltage range. Makes no sense in this application to boost the voltage only to drop it later. If you choose a buck converter followed with a boost converter (more cost effective design since the inductor can be shared), design the control circuit to only operate the buck or boost sections at a time. (Leave the buck transistor on when boosting and leave the boost transistor off when bucking.) A buck/boost design will have even fewer parts, but the transistor and diode must be able to withstand the maximum peak line voltage plus the maximum pack voltage and some margin.

Alternatively, since the difference between a bridge rectifier and a voltage doubler is the capacitors, use a relay to switch between bridge and doubler operation. For the bulk charge, disconnect the capacitors altogether (except through some large resistors for precharge) and operate the buck converter. Once the bulk charge finishes and the topoff charge starts, switch in the capacitors to give the buck converter more voltage to work with. (The peak voltage for 120v AC is right about the correct charge voltage for a 144v lead acid pack! In fact, I remember reading about someone who made a large UPS with little more than 12 12v batteries and a bridge rectifier.)