Front spring eye height setting.

Ok so here's what I have been rolling around in my head. Maybe racers can help me. I'm going to make a trip to the dragstrip with my 68 Dart this summer. Street tires just to see what it does. It's got the US. Car tools spring relocation setup on it. That has 3 front spring eye holes. I've got 296/50/15s on it and they clear fine on any of the settings. The middle one is stock ride height which is where it is now. Do you guys see an advantage for me to move it one way or the other before my trip to the track? I've tried the top and middle which is stock ride height on the county road. Couldn't tell any difference there as it just blows them off anything past 1/3 throttle and doesn't get much weight transfer. Oh also guesses for tire pressure? Thanks in advance for opinions.