Clarification on 70+ alternator VR on 68 cuda

Looks like I have the wrong alternator then. Pretty sure I need a 20153 which is a 60 amp with 2 field terminals. I wonder if my regulator isn't for a 60 amp then? And can I solder the new wire from the alternator to the existing blue ignition wire where it will be cut for the new connector? And what gauge should the new wire be?