Hello, I recently acquired a 1968 GS 400 convertible, and I was told it was original. However, the valve covers say 430-4. Is it possible it came from factory with the 430 or was this not an option in 1968 for the GS 400? I have read that 430s were only available in the B-body and all GS 400s in 68 came with 400. Is is possible to obtain the original build sheet from the VIN? Thank you.