In your quest for consistant 60 ft, i had excellent results by launching at a low throttle setting using an ACD co2 throttle controller. When i graphed out my throttle position at the hit, i leave at 4000 versus a stall of 6200. That throttle controller takes .05 to open fully, then add a whisker of time for the air to get to the cylinders. Basically is really lessened the "hit" for the first few inches, dramatically reducing the violence of the hit. My dart has a 11.17 SLR, 980 hp and 2900 lbs with short 30 inch ladderbars , Afco big gun rear shocks to deal with all that torque. My 60 foots have been spot on within .002, going 1.224 to 1.226 same day.
The point of this info is to show how much that softer first few inchs of launch helped my dart. It used to smack the 66 inch long wheelie bars hard, then spin, and only go 1.27 or so 60 foots. The one thing it did change was my delay box setting had to be reduced by .05 for decent lights.
There are a lot of ways to skin a cat. If you still have 60 fts varrying more than .002, maybe trying to soften that initial hit will pay big dividends like it did for me