When you increase the cam size, the duration goes up. The power band moves up in RPM with a bigger cam. He already has the BEST cam for his combination now. The stock cam. There's not another cam that will likely improve bottom end torque with the rest of his combo. What I would do would be to work from the rear forward, starting with a decent gear FIRST. That way, there's less disappointment and with each change there will be power he can FEEL.