Before I finally broke down and bought the ARP extended lugs, I did a lot of reading on this. For street use . . . 7-8 turns of the lugnut is allegedly fine. I know you're looking for the wheel spacer width, but the reality is the type off wheel plays into it also.
The ARP studs are relatively cheap and super easy to install. Consider doing it, if you have any doubt. I used ARP Part #1007708. The old lugs come out with a wack of a sledge hammer. The new ones go in with a wrench or impact and a cheap little tool meant to protect the rotor hats. Lots of "how to" online.