back up light switch

If you do have a reverse lamp switch on this 68 model column, you also have a single function / 1 wire neutral safety switch in your trans. All of this changed sometime during 68 model. Reverse lamp switch moved to the trans, a single location regardless what manually operated shifter is installed.
So the later design 2 function / 3 wire switch for the trans wont work ( unless you change a part called a rooster comb inside the trans ). The column mounted switch typical of 67 and earlier that you have is totally different from the switch that mounts on the floor shifter. There may be a switch for/from a aftermarket shifter that will work.
I always look for the OEM correct parts first. That's the correct shifter mounted switch and the OEM floor console harness which is basically a extension cord that plugs into the dash harness connector that did plug into your column mounted switch. That console harness will have a orange lamp wire in it also. I forget where that wire tapped into the standard dash harness. May be at the same lower steering column area where that column indicator lamp is no longer req'd. There or they tapped it in before the ashtray lamp which would have been their least expensive route.