My old '66 was as low as you can reasonably go up front. On medium bumps the tires would rub the inner fenders and on big bumps the crossmember would bottom out on the ground. It had 215/75-15 tires, drop spindles, and 1.5 coils cut off the stock springs. The bump stop brackets were completely cut off and the shocks were relocated to regain full travel. The rear had a 2" deep pipe notch with relocated shocks and never bottomed out. Any lower would need a step notch and raised bed floor to keep enough travel to keep from bottoming out.
