3-2-1 is only a guideline and needs a temp in the area of 225-235 or so.
Cook hotter and it will take a lot less.
I cook Baby (Loin) Backs at 260-270ish for about 1.5-1.75 hours, foil them for .75-1.0 hours, then sauce and put back in the smoker just long enough to set the sauce--maybe 15 minutes or so.
You will need to experiment with them so see just how they cook up on your cooker to get the results you want.
Keep us posted--OK?
"Flirtin' with Disaster" BBQ Team (RETIRED)
FBA and KCBS Cook and Judge.
Former owner of a WSM, a Smokey Joe, a Charbroil Commercial gasser (junk), the legendary "StudeDera", a Fast Eddy PG500, and Sherman.
Now cooking with a Yoder YS640
Proud Pellet guy cooking on real wood.