1970-1971 340 valve covers are all the same (factory originals that originally came painted orange). That said there were two versions, a very subtle difference, one with the spark plug wire separator loom stands that is placed about 1/2" closer to the end of the cover than the other version. Some will say that the version that was closer to the end is a TA/AAR specific style, but I've confirmed by examining multiple survivor examples that it was not, the use of these was random during 1970 & 1971 model year.
The engine color change from orange to blue during 1971 production model year took place when the engine plant change was made from Windsor Ontario Canada to the Mound Road plant in Michigan. This took place sometime around April 1971. So, with your car being built in December 1970, yours was most definitely orange when new. For others interested, further examination of thier original blocks can confirm the engine plant it was made at simply by checking the assembly information stamping on the front of the block just below the drivers side cylinder head.

Bottom line, these are original 1971 340 covers, yours should look the same. The second pic shows both versions of the spark plug loom stand discussed above.