This isn't a major contributor to why it isn't any quicker, but why did you go with the Dana 60 behind a 318? The Dana is both heavier and 'eats' more horsepower than an 8.75" rear end. I bet it may have cost most than an equivalent 8.75.
The shop recommended it. They claimed they would have the engine running tip top, but they delivered the car without any tuning. they just installed the stuff and got my money.
