thats not such a huge difference in weight, considering you've probably cut weight to make your bouts weight limit.
what I'd do anytime that happened was to be sure to show up the next day to do it all again with the guy that got over on me. you should have a considerable advantage in speed, go out an get off on this guy first, work you speed and movement. Then start feinting and drawing him out then capitalize.
I was fighting at 147 and my trainer had no problem throwing me in with heavyweights. You gotta be sharp with your eyes, I found that the bigger that they were the slower that they were.
One day I come in to work and they tell me that I'm sparring with Dennis Andreas that day. I knew who he was because I watched Thomas Hearns take Andreas LightHeavyweight title at the Palace.
While it was an intense few rounds with him coming hard for me at times it was relatively easy, he just couldn't handle the speed. Rat-tat-tat and get the **** outta there, rat-tat-tat etc.
Being smaller is only bad if you allow it to be. You have to take your strengths over him and make them work for you...........Rockin'