ride height question

per the FSM the ride height for my 68 Barracuda should be 1 3/8 +/- 1/8

I have read that the ride height needs to be set prior to an alignment as later changes to the ride height can affect the alignment.
I have also found the Skosh Chart with recommendations for caster and camber.

so my questions are
1) is the OE ride height specification still a valid requirement and that is what folks run?
Or with changes to tire diameter, stiffer rear springs and stiffer front torsion bars do folks tend to set the 'stance' they are after, lock down the ride height, then move forward with the alignment process.

2) and for best straight line stability my thought is that a car that is level to the ground would be the most stable, all other things being equal. I am defining level as a car with the same ground clearance at the front edge of the rocker panel to the ground and at the rear edge of the rocker panel to the ground. I am thinking that with stiffer rear springs I may need to bring the front of the car up a bit to level it. Hence the ride height question...