That is a great practical - rather than simply theoretical - test platform.
Yes, I should have been more specific. This would be using a repro 1960s pickup - either a Thunderbucker I have or possibly one of the recent Chinese repros.
There is some subjectivity to the word "optimum", it's true. If the desire is to approximate the sound of a '60s bird, then the optimum is clearly the same position as original. I meant, any perceived advantage to deviating from this from those who might have tried (?)
My personal optimum is close to an original '60s TB II but with perhaps a touch more definition (thinking more about live use) but without taking on the overt characteristic of a soloed bridge pickup. I'll probably just play it safe and put it in the usual spot.
I've read through some of the Talkbass threads and pup placement is clearly a well tread topic; unsurprisingly, people have strong and usually contradictory opinions.