how much alternator do i need?

Wondering how many amp alternator i will need and how to figure it out. Car is a 70 duster. I am running electronic ignition, holley blue pump, msd al6, electric radiator fan, and all the stock lights. I have a new 65 amp alt right now. Should i teade it in for a bigger one? Also do i need external or internal regulated and is there other vehicles i could steal it from?