I have a one piece from Art Carr which is C4 splined. I run an edge racing 3200 non lock. Given overdrive wont be the same as with a lock up, because my converter is constantly slipping, but i do have overdrive.
You need to get o/d out of your head when talking torque converters.
The band applies on the rev. drum and you get o/d and has nothing to do with the TC. Lock up or non lock is simply no slip or slip. The change is in the TC with the small shaft, it slips into the splines on the TC cover (the part that bolts to engine) and turns at the engine/tc speed, when the direct drum clutch is applied you get 1 to1 because the other end of small shaft goes into the direct drum.
Now lets say the splines in the TC are not attached to the TC cover the small shaft would not be 1 to1, it would be non lock because the splines are attached to same hub as the forward drum, so in effect they are as one which is why you can buy a 1 piece shaft for non lock.
I hope i got this right.
Miine was a lockup and my susp. is simular to yours but my 60 ft. is only 1.71 best.
I have 3.73`s, do you have 4.10`s I was thinking of going 4.10`s this year but was not shure of what change i would see. Shure like to know if thats the gear your running.
Do you post on click click forums, that pic of your car looks familar.