Need Help Finding a Starting Point

you might try 7lbs in the slicks. you could start at ten and keep going down until it starts to sway on the top end. i've found that this starts to happen at 5lbs and my hotrod with the same big tires you have settled in at 7lbs. make sure you ladder bars are set up neutral and the front and rear springs are the same length, front the same, rear the same. i think the wheelie bars are supposed to be 3" off the ground. sounds like you have the shocks real close with carrying the front for 20'. how far were the fronts off the ground?