[G_Edmonds]

Dan,
Ideally your torque convertor should be matched to your camshaft duration.
A real light car like a cobra changes things a little different though. A tight conv. wants to pull thru at stops but one as loose a yours will hardly ever "engage". This makes your trans run hot (not good for longevity). basically in a car that is not a race car selection is a compromize. A lock up would be a good selection but I'm not aware if any are made for the C4. They are usually built for overdrive transmissions. With the torque that a 489 makes, you can go a little conservative because you don't have to be right at peak torque rpm when you leave the line.
-Greg