1935 coupe seat

[35cab]

Looking for a bit of advice:
I am putting together a 35 coupe seat, I have original steel base, wooden base and back plus lift up sections, new start springs etc. I made new seat side panels from plywood copying an original set.
My question concerns the upholstering of these side panels: do they get upholstered off the frame and then attached to the steel base or are they upholstered / covered in situ?
I ask as when the panel is attached to the seat base there does not seem to be enough clearance between it and the metal panel for upholstery.
I could easily trim the wooden part down at the point where it meets but as I say these are copies of original panels.
If anyone has a picture of an upholstered seat frame it would be much appreciated.
I hope this makes sense.
Thanks in advance.
Gordon.