Not surprised as most cars of that era did not have Gas pressurised strut inserts, Seems everyone forgets that Gas pressure struts do act as very effective helper springs and that will be most of your problem.

Some are worse than others, I remember when one of my Works Stanza Rally struts lost gas pressure the front of the car on that side went down by about six inches as the gas pressure was so high in them.

But I have seen Datsun 1600's fitted with the old Tokiko Gold inserts pop up a couple inches in ride height after they were fitted needing different springs just to bring them back to stock height and that was with the drivtrain in place.

So in reality ddzongal is right on the money and the above explanation is why.