depends on everything else though, ie. headlights, electric water pump, alarms, you could run 100 thing off of one alt. painless wireing also makes a kit for your 70 to swap your headlights out for ones the have an actual bulb and not a sealed lense, then you can swap to an HID light. 100 bucks from painless and 55 for HID lights at
VvMw.com | Vv Mw thats for the pair. i did these on my 69 and loved it