Closest place to find deathclaws from Goodsprings is Quarry Junction to the East and just North of Sloan. Unless you have a high guns skill I would stay clear of them. Shotguns have a low firing rate and have to be used up close so it gives them time to jump you. Not good since they can kill in two swipes. Also, Deathclaws come in packs in this game and if you have to fight more than one at a time you are toast. The best way to deal with them is sniper at extreme range.
Agreed. First 'claw I came up against was near the quarry (just north of it if I remember correctly). I used the gobi campaign scout rifle (A regular sniper rifle would work fine) and I was picking off deathclaw heads left and right. However, the mother and alpha 'claws gave me a little trouble, being able to make it past the first shot, and even the second shot. But I was only using normal ammo.
An Anti-Materiel Rifle with AP rounds should put any Deathclaw (or any creature in the game, for that matter) down in one sneak-attack shot. Even easier if you have better criticals.
I want to use my YCS/186

I love this gun. I am going to go to the quarry as soon as I get Meltdown