is there a way to get a scope for the paciencia hunting rifle?

Nah, it's a unique weapon.

You don't need a scope with Paciencia. When you aim down the sights, you get magnification equivalent to that of a scope.

The magnification is pretty amazing, but it suffers from the same flaw as the unmodded Hunting Rifle. It's sight is very slightly off which makes long range shots a bit of a gamble.

If you're on the PC then I suggest downloading a mod(WMX is a good one), if you're on a console then I suggest using it as a mid range weapon only. It still has a pretty insane critical hit.

Yeah, I must second Lobotomite's suggestion of http://newvegas.nexusmods.com/downloads/file.php?id=39651. It's amazing.

Enter thrid person mode hold down aim and enter first person mode while you still hold aim, this might help you.