Hi Ian,
their are quite a lot of differences between Replica bodywork and original bodywork, best to go with replica bodywork on a scratch built car I reckon.
Front clip is radiused across the nose on original but GTD for example is fairly flat, doors are a different shape, rear clip differs considerably also.
I have noted that the KVA type bodywork is reasonably similar to the original shape- but there are a lot of variations on that anyway, overall- the cars all say the same thing, GT40.