The finish on this car, inside and out, is far better than when it was new. I agree the seat looks unusually clean but it looks to me like it's pretty close to original but maybe with more padding. When raced, these seats were usually dirty from having been stood on and had oil spots etc.
We had a small Italian car (OSCA) of similar vintage way back when, and it was built using pretty much the same techniques as this one (large tube frame, superleggeria (sp?) body construction) and it was hard to get in & out without bending something or at least getting it dirty. You couldn't put much weight on the "floor", because it was a removable belly pan of thin aluminum so you found a frame tube or the seat itself to plant a foot on.
Restorations to this level of quality are beautiful to look at but don't show the cars as they looked back then. Here's a shot of a friends Lister Jag when it was about 4 years old - note the dents, scratches, etc. To me, this is what old race cars ought to look like and I hope the trend to preservation rather than restoration continues.
Didn't mean to turn this in to a critique of a fabulous resto effort.