Depends on what you want to do with it. If you just build it as is, you'll run into issues with the mirror cowlings which are entirely the wrong shape and don't really fit the body well at all. These simply have to be fixed somehow for a good looking result. My way was by making new ones out of styrene and milliput.
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Another issue that needs to be addressed is the windscreen. Mine was too wide, so I had to bend it inwards on the sides in some hot water. Though I ended up not using the windshield and making a new one out of acetate, I did successfully bend the original to nicely fit the opening, so it's possible. The other option I see is to glue it in with cyanoacrylate before painting the body, but there's several reasons why you probably don't want to do that.
If you successfully fix those two issues, the model builds up nicely out of the box. There are no massive fit issues or anything like that.
But if you want to go the extra mile...
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The shape of the (hinge cowlings?) is wrong. Too square. I fixed it by cutting the body in half and reshaping them. As a bonus fact, the vast majority of miniature reproductions of this car (kit or die cast) get this detail wrong for some reason, even though there are plenty of photos showing that these should be smooth in shape.
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The rear end is wrong. The real car had what seems to be just a piece of sheet metal covering the mesh. The sheet metal piece basically doesn't exist as the kit is molded, so I redid the rear while adding some proper mesh and bolt detail.
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There is no engine. Which is fair enough, but it does leave an empty area where it should be, which is visible if you peek around the rear wheels or from below. I scratchbuilt a really basic engine shape and designed + 3D printed an exhaust manifold.
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It's admittedly not the prettiest work, but this area is barely visible when finished anyway.
The lower right side of the car is missing an air intake (This style of intake is specific to the #21 1967 LeMans car. Others had a different shape or no intake at all).
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This little scoop is also a really weird shape, so I made a new one.
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The dashboard is a mish-mash of 3D printed, original part and sheet styrene. The biggest inaccuracy is the instrument cluster, which in the kit only has one dial instead of the tri-part one.
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I also spent a stupid amount of time redoing all the riveting. I punched the new ones out of foil from a yoghurt cup.
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I made the windscreen wiper out of wire, tubes and styrene.
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Plus many more small fixes and complications. You don't need to do all of that of course, but it shows what's possible.