Lower end Shimano (Sora/Tiagra) cranks are usually offered in 165, but in 5mm increments and they skip the 167.5 and 172.5 sizes and top out at 175mm. I know this because I need 170s or 165s, my bike should have come with 172.5 based on size, but it came with 175 because Tiagra skips that length.

I was also under the impression that Campagnolo shifters don't actually work well with SRAM derailleurs, even though the average cable pull is the same, SRAM uses even cable pull for all gears and Campagnolo doesn't. Campagnolo mated to Shimano with a shiftmate would probably perform better. Only a guess though.