The original only had 6 tentacles (should we change that in our writeup?) presumably to keep the other two free for manipulating things and didn't get a Str bonus. Taking 1d6 tentacles at 1d2 each gives an average constrict damage of 3.5*1.5=5.25. 1d6+1 gives an average of 4.5, which isn't that far off. And that's assuming that you get lots of tentacles attached as much as just 1 or 2. I just don't think we should compare constrict by adding in Str for each tentacle, since that's not how constrict generally works in 3.X. We've done some exceptional constricts in the past, I think, but those were for more exceptional monsters, too.
I do think we should add the shortspear to the attack line as a possibility.