Chris,
What exactly does "doesn't work that good" mean?
I presume it's lost sensitivity as the tip can't support the extra weight, but it would help if there was a clearer explanation.
Being a Tuna rod, it's not going to be designed for sensitivity.
If he's hot for E Glass then the BT655H may help in that regard.
What's the target species and style?
You might get better results overall with a GF755H for that weight or a maybe a stand-up blank like a Batson RCTB56H.