From the perimeter than the paint. In fact, I would rather focus more on stopping guard penetration than allowing them to have a wide open three. Fact is, scoring is much easier when you are doing it in the paint. You close that off, then you will win way more than lose. Of course some teams will be "Red Hot" from the perimeter, but not all the time. In fact, I would say not more than 20% of the time. I go with those odds.
Wide open threes and points in the paint are the most efficient ways to score. If you close off the paint at the expense of giving up open threes, you're not really going to be successful. The trick is to make them shoot perimeter jumpers that aren't open threes. Contested threes or less-contested long twos. Portland needs to be able to cut off guard penetration while still contesting threes. If those guards penetrate and pull up for two-point jumpers, that's acceptable.