Try the Wilson Energy Rail XL, the cheapo alu frame found in the big stores.
I had one that I shortened into oversized child racquet. Before that I had it leded up to about 340 SW. It hit big monster serves and lots of spin and had VERY soft flex. However the original high-frequency chatter vibration just changed to low frequency vibration that I still couldn't stand.
As the other posters said, you'd be much better of with any oversized graphite frame...
It's never too late for a happy childhood!