Your ammeter is moving so it is good. Yes you can drive the car 25 miles with no charging just slow charge it up on the battery charger later when you can. It's not the best for a battery but not a 1 time deal breaker. Your alt is good. there's a reg or reg ground or field circuit (blue/green wire) problem. The simplest/best tool other than a VOM is some made up jumper wires with alligator clips on each end. Take off all field wires from the reg and alt and jump from the batt positive post to the "ign" reg terminal and from the reg "fld" terminal to the alt male field terminal & with a good alt and good reg & reg grounded it WILL charge. then figure out which of the wires you took off has an open (or is wired wrong) EDIT we posted at the same (approximate) time. You have the original 68 type "box" reg? and a 2 field terminal alt? then yes ground the 2nd alt field terminal (pick either one) to ground and the green wire to the other field terminal