Does your SZ have the mechanical stuff at the top? You may be able to construct a removable section there that provides the needed air flow and carries the soffit face and trim if needed in that section. In effect, part of the soffit front is now attached to the SZ air panel enclosing the upper unit structure.

SZ unit images and sizes may be of help here to minimize guessing.

As an aside, you may want to obtain some stainless steel (1/8, say) plates for the wheels to roll onto to keep from having that weight depressing the floor in small areas. This thickness will affect construction at the top. My 632 sits on stainless plate on top of 1/4 hardwood plywood on a cherry wood floor. This makes it easy to roll the unit out onto sheets of 1/4 plywood if needed.

This is the unit and measurements, you can do shorter grill and make it 83"

Which model are you using? Designer or Classic?

classic

If it is 83" with the reduced grill, doesn't that put it under the soffit that you wrote needed 1/2 inch removed?

No there is only 82 1/2 because of flooring over flooring

Clarify
There is 82 1/2 inches from floor to soffit
Min needed is 83”

One other thing I had to work out for my 4-ft wide SZ. The refrigerator's diagonals are longer than its rectangular dimensions. (Your unit's diagonal's are nominally 87.4", 91.4".) If the unit has to be tilted to get to its destination, perhaps to get it through a doorway, be sure it can be re-erected without a diagonal intersecting the ceiling or an island or peninsula. Your ceiling at 96" should be OK, but the potential spaces for rotation look tight in the images.

Edited: 14:14 24Jul22

I would really like to just redesign the cabinet. So looking for ideas on how to do that without disrupting the area behind the oven.

Anyone willing to revisit this design dilemma?

Would you be able to just remove the upper cabinet And cut a bit out of the soffit and re-trim and mud that or put some kind of new molding stained to match it ? It would take a lot of fiddling, but otherwise I think you end up having to tear out that side and having some impact on the range area.

That’s what I am thinking to. Just the how!

A certain amount of ravaging will be needed. It will mostly be visible on the inside, where the refrigerator will make it hard to see. A tool that may help get that shelf out of the way and perhaps even some of the soffit is among those in the link below.

https://www.popularmechanics.com/home/interior-projects/g1763/best-oscillating-multitools/

It is very hard to be specific about detail finish carpentry from a distance.

One could even rout down the damaged areas and glue on veneer if perfection is the goal, or veneer the entire inside panel area.

I do think it wont be easy for sure!! we have the lath and plaster walls and they are not easy to modify!