1.5 lbs would be a very small chunk of loin.
Sure you don't have a couple of "tenderloins" there? That would be a totally different animal! Or maybe a small pork sirloin roast?
Please post a pic so we can see?
As to time? That would go in a heartbeat even in smoking terms for such a small amount of meat?
Don't cook to time, cook to internal temp!
I would recommend 130 to 140 for that small piece of meat. With a rest they should reach the required 145.
Then again? If your family thinks pork should be cremated?
Another problem altogether?
Good luck and good smoking.