It depends on the ride height of the car. The generally accepted ride height is 27" from ground to edge of wheel opening, measured at the wheel center line. Phase two BJ8's are usually given as 28" at the rear. Since no two cars have quite the same body panels & assembly, or suspensions, these heights can vary noticeably. I can't image an actual six inches of ground clearance on any Big Healey. If the rear suspension is set too high, there is not much rebound travel available & the ride is terrible. Maybe others will give the numbers for their cars.
D