Looks like a shoulder roast to me. These are very nice smoked like a pork butt i.e. through to about 200F and pulled. I do them to that temp both on a rack and on a roti, roti is even better.
Oakridge Santa Maria would be great, I have used that. Lotsa garlic in the rub is good. I have also done smoked to about 120, then put in a thick mix of redwine, garlic, onions etc and finished to about 150. Lamb loves injections.
Generally best lighter on smoke than heavier.