wich sm block tunnel ram

Torque?!?! You have a 4 inch stroke. Shorter runner higher RPM. You never said what RPM was your limit. I figure, if your going to run a tunnel ram, your turning up the wick real good to burn real bright.

In that case, I think your head flow falls short and your gear ratio is numerically to low.
Head flow in the low 3's min and 4.56's with 32's. I'm not sure about the converter, but I myself would go to 5,000 and a trans brake.