I assume we're talking the 74mm ring on a 110/74 or 130/74 crankset? The OP didn't say what his crank was specifically(just older, sq. taper), but all of mine rely 100 percent on spacers between the inside arm face and the granny ring. These spacers are made in all the thicknesses shown in the links above. I believe my old Sugino AT triple was in the range of 3.8mm or so, give or take, for instance.