I assume since you changed the starter your problem is the engine won't turn over versus not firing. Also assume you cleaned up the battery cables already. The 72s can have a start problem due to the ground cable. The ground cable screws into the alternator bracket with a small screw. If the cable is junky looking, the screw is loose, or the bracket is rusty, the car will have start problems. I have changed out a starter just to learn this. If this is OK maybe next check for voltage on the starter. That's at least accessible. I use a clip lead on the starter terminal instead of trying to hold the meter lead up in there. Clip the lead on the "S" terminal and the other side of the lead goes to the meter. Other side of the meter to a good ground. See if there is voltage as you crank the key. Check to see that you did put the purple wire on the "S" terminal. If the yellow and purple wires are reversed, the car won't start.
After this it's time to start looking under the dash. Post back with your findings.