Actually, you can...
For a vehicle older than 30 years you can buy license plates that was right for the year when the car was first registrated.
But if the car had a Norwegian serial approval that says what kind of plates to use, you have to go by that. For your car there was no such approval. You can call for example Lator Skiltfabrikk (55 36 26 90) and order plates like they was in 1979. You can choose the size, from the different sizes that was used in 1979.
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