Plymouth Valiant:
http://en.wikipedia.org/wiki/Plymouth_Valiant
'61-'62 106.5" wheelbase curb weight 2750#
'63-'66 106" wheelbase curb weight 2692#
'67-'73 108" wheelbase curb weight 2743#
'74-'76 111" wheelbase curb weight 2819 #
Adding 2" to a cars wheelbase makes it heavier not lighter.
Equally equipped, the Gen II W/the shortest wheelbase should be the lightest as evidenced by the above
The "A" Body Dart started out @ 111" so it's not even in the running.
The "A" Body Lancer would be the same as the '61'62 Valiant.