would australian shepherd make good narcotics dog

Good is a relative term. In my opinion. I think that an A-S would get the job done.
But, if you are looking for a strait drug dog, and you are starting from scratch and looking for a dog type. I would say there are better options.

what would an A-S have that would keep it from being a top drug dog

There are individuals in the breed that would do very well. But you really need to do your homework and find a good working bred dog or go to a rescue group and find a young adult that shows the needed drives and temperment for the job.

I think a better option for a new trainer/dog handler would be a good working bred lab.

Mara nailed it. There are individuals in lots of different breeds that make good drug dogs, but breed alone only gives you "tendencies" not ability. The ability is in the individual dog.

my thought for choosing the A-s is that i was raised around the A-S in the sandhills of nebraska, and after reading more about the stress levels of a drug dog,i thought what better than one of these old type A-S, to explane more why this dog could handle stress in my opinion is, we would load out 2500 steers to be shipped in the fall ,these dogs would work all morning sorting cattle in pens, with gates banging, hired hands hollering to close the gate, or stop that black steer, 18 wheelers backing up to chutes ,truck drivers coming up to you to tell how many they could put on top deck ,and the dog accepting a stranger like he was just another hired hand,we would go to lunch he would lie by the front door of the cook house,go back after dinner and work all after noon and some times into the night depending when the trucks would show up, so the stress for these dogs was unbelievable.now that i think about it the noise, the livestock was huge,the hired hands were always shouting, and most of the dogs work was done with his mouth ,because we wernt herding sheep , we were loading cattle in close quaters and to move them was to bite them or bark.doing all of this and still staying focused on his handler . now not all the dogs could handle all day but the good ones could,that's what made me think they might be good for drug dogs ,they could work a busy terminal or road check, i think they handle the noise and people and stay focused.

No doubt they are workers, Bartt. I hunted grouse in the NE sandhills north of Lisco. Originally from Scottsbluff. Small world. I have an uncle who keeps working Border Collies to work a large cattle heard in the mountains in California. It's truly amazing what those dogs can do, and I know the Aussie is similar.

A cattle roundup is an impressive event, and to see dogs working it is something special. Thanks for bringing back some memories!!