One BIG difference in a normally-aspirated V8 car (small blocks in particular) and a turbocharged /6 is that in order to get the best quarter-mile performance out of the V8, you need a rear axle ratio somewhere in the mid-to-high-4's or low 5's so that the engine is at its power peak as it goes across the finish line... usually around 6,000 rpm or higher, whereas the turbocharged /6 motors seem to like final drive ratios in the high 2's, or low 3's, making them good street cars in terms of rear axle ratios.
I know this sounds bizzare, but Ryan's car and Ton Wolfe's cars both have responded to this practice the same way; they have gotten faster and quicker as they have each changed their final-drive numbers into the twos.
Something about a turbo engine responding well to "being held back" like a nitro motor...
That would seem to nullify both the utilization of a manual 4-speed overdrive and the avoidance of a 904-type automatic transmission, as highway driving would be ideal with the 2-series of final drive ratios with the turbo /6 engines!!!