How low safely?
 

Curious how low you guys are going without having to get out to check clearance all the time. I've mocked mine up with crossmember 5" off the ground and I think it needs to go lower. However that's gonna put the oil pan and bell housing really close. I'm guessing those will be 3.5" or so.

Honestly it depends on how careful you are driving. I've drove my 69 for years with the subframe 2 1/2" off the ground. Pan was a bit higher but exhaust was lower! Lol. Yes, it did drag a lot tho!

I did see another thread that mentioned 4" being about the lowest for street driven cars.
The consensus was that you can get away with some lower points where the axles are because at least in the case of a driveover curb or speed bump the wheels raise the body to clear the bump. In the case of straddling debris or bumps all bets are off.