I didn't know you were trying to optimize this for a 1/4 mile in the v12 107.

What I would do is look at your projected trap speed and gear it around that. Generally you want to be a ready to shift (but hold the gear) right at the line. You can theoretically gear a car so short it hurts 60 foot time but that would be a challenge with Mercedes ratios.

Your trap speed doesn't change nearly as much as your 60 foot time or et from gearing. Do you can do some passes and record a trap speed and leave some headroom. What's your trap speed currently?

Also have you looked at a looser torque converter? In domestic cars a cheap way to get a loose converter is to use one from a smaller engine like a 4.3 converter on a 5.7. I'm guessing the v12 has a pretty tight converter.