Here's my version of your build ( using Throwing knifes from behind ) : 3 Strenght has a range issue
https://img15.hostingpics.net/pics/991242Sneaky.png ( Nuka/Cigs the picture is under drugs )
http://www.hostingpics.net/viewer.php?id=295103Sneaky2.png ( Nuka/cigs/buffout/jet ) This one is not under drugs on pic
With heave oh! acting as a throwing weapon handling on top of adding 6 range you're at 5 str
The 9 agility and perception become 10 with nuka and cigs ( the only drugs you need with this.
A variant with 1 END and 10 agility will allow you a combo of nuka/jet/buffout/cigs for a better rate of fire at the cost of some hp's
The luck loss is very small considering you have an auto critical from behind, get some shortuc to firstly aim the groin instead of head then head for second shot. I'll do the 1 END version like this you'll have two builds to look at.