Wow, I hate to see that. The Montello model is the premium Pinarello from that era, I'm sure you know that. You say you bought it for the fork, I would say just go with that and don't pursue a repair of the frame. That's just my my opinion, of course, but everything that makes that frame special won't really be the same, even with a professional repair. I own a lugged steel Pinarello myself, love it, best road bike i've ever owned, etc, etc. I'll say again, I hate to see that damage to that frame, but I think I would just retire that one.