1970 lemans turn signals inop. replaced blown fuse, then flasher, still no good. should i go to steering column next

If none of the signals work then the column switch would be a good suspect. However, before tearing it apart, have you checked the bulbs and sockets? If the contacts are corroded they may be in need of replacement rather than the switch. Also, did they just stop working or are you restoring the car and don't know if they even had worked recently. Try using a volt meter to trace back where you are losing the signal to the bulbs. Not much else to the system - switch, relay, wires, sockets & bulbs.

Also, check the fuse again. Maybe it blew a second time and you have a shorted wire somewhere.