The 1/32 kit's seat is OK, since it's correct for an F-100D, but you can replace it with a resin one for better detail. I like AMS Resin's seat. It's very nice.
I would bet Trumpeter just used the F-100D cockpit for their C as a cost-saving measure, since most folks probably wouldn't care. If you don't want to wait for AMS's upcoming F-100C cockpit, you could start with a seat from a Pro Modeler F-86D and modify it slightly and get fairly close to a C seat.
HTH.
Ben (F-100 Nut with no affiliation with AMS Resin )