My Boston experiences were a long time ago ('79 and '80) but I learned something about the Newton Hills that might help you avoid trouble there.
They're not easy, but I do think that some of the difficulty's in a runner's head. When I ran Boston, I ran with a friend who was just a little faster than I was in short races. We trained in flat Buffalo. Both years, we headed out on a mid-2:50s pace and were motoring along just fine until the hills.
Then, two years in a row, my friend said, "Can't do it," and dropped way off the pace. I finished both times as planned, mid-low 2:50s, and he ended up far behind me (I can't remember for sure, but I think over 3). He would never talk about it beyond saying that he just lost strength.
I don't think he was having physical problems. We had trained together, our training went well, etc. If it had been just one year, I probably wouldn't even be remembering it. But two years -- same spot -- same reaction -- I think it was somehow in his head.
So I suggest paying careful attention to what you're feeling as you approach the hills. It might be nothing more than apprehension. Attacking the hills wouldn't be smart. Just motor up them at a pace you know you can handle. That's really obvious advice, I know.