Very nice bike. I just picked up an '82 613 a month ago and am loving it. Mine was close to NOS condition. I regreased the hubs & BB, polished out a bit of rust and hit the road. That third chainring of yours interests me. Was that just added to the original crankset? Sometimes I wish mine had a super-low gear to spin my way up some of these hills.
No idea about the cable clamps -- mine has braze-on cable guides for the rear brake.