Need some thoughts on my plan. I have a small 1 level ranch in MA. The basement was originally finished and i am renovating. But when they built the house, they made the basement ceiling height only 78.5″ high. Meaning when i get to the bottom of my 1 turn winder basement stairs, the last step technically hits my head because the rim joist running across the steps is only 70″ high from the last step. as seen in the pics.
I CAN survive, but there are 2 things i want to do, and ill explain why.
1- i want to eliminate the last step so that i step on the ground before i get to the doorway threshold along the rim joist. basically it would be pushing the last step back almost “tread depth” This would eliminate the need to have to duck before stepping down on to the last step.
2- on a completely separate plan, i want to make the “straight” steps ( before it starts to wind) terminate at the doorway threshold. Which means the remaining steps will only be as wide as the doorway entry opening. This is why: i want to make those remaining steps built on some sort of large “slider”. The reason is so i can pull out the doorway wide steps to leave a large  opening where i can lower a fridge, or other large item, directly to the basement floor without having to maneuver a large item around a turn in steps., then “slide” them back in after i bring large items in the basement. Right now one tread stops just past the doorway entrance, so i would need to push all the treads back slightly, and then, also somehow eliminate the last step as mentioned in my first issue above? I know none of this would be up to code, but, i think the benefit of both ideas will far out weigh a mismatch in tread depth and hight max/minimums.
current measurements on each riser is already mismatched from the builder of 9 1/4 to 9 3/4 with top and bottom step much shorter. non of the current steps are equal height.
ground to top floor is 88 inches
ground  to joist is 78.5
last step to joist is 70

distance from top floor to door threshold is 40 inches out ( this is where ONE step needs to terminate so i can put the remaining steps on a slider
take a look at my pics to help give you an idea of what i am talking about