The MP Chassis book says to measure from the back of your rocker to the ground, then measure from the front of the rocker to the ground and that the front of the rocker should be one inch shorter.

I don't know if this applies to cars with Cal Tracs too.

I'm at a 1.68 60 foot and 7.86 1/8. I think that's a pretty good 60 foot for what my car is and the times it runs