65 VIN Rivets

[ChevyK10Dan]

Hello Everyone,
I am new to the site but I have owned a 64 K10 short bed for around 7 years. I recently bought a 65 C20 from a friend of the family for $200. It has no engine or trans but the cab is rust free.
It has a little damage to the driver's side rear cab corner but nothing major. He bought it in 68 and it has been in the central California area all of its life. It does have some rust in the doors and fenders and a little bondo on the bed but the cab is rust free.
It also had the power steering, power brakes, auto transmission, and custom cab options.

I plan to use the 65 cab to replace the rusted out cab on my 64 but I had some questions I thought I would ask first.

My 64 has the VIN tag spot welded to the B pillar like it should, and the 65 has the VIN tag riveted to the door jam above the door like it should be.

The pink slip says the C20 is a 65 model first sold in 64.
My concern is the type of rivets holding the VIN tag in place. They are normal round rivets not the flower shaped rivets I have seen on later years.
The VIN on the frame matches the cab and I have a pink slip in my name, It has the original rear black/yellow CA license plate too. The truck is on a planed non op to avoid paying registration fees.

I have seen another 65 model year in my area that has the round rivets and not the newer flower shaped rivets, but I was hoping someone with knowledge on this subject could help inform me if this was done by the factory/dealer or illegally.

Did GM use round rivets in late 64 on the 65 model? I have seen others bring up this topic on GM full sized cars but it would make me happy to hear from others that have a GM truck 65 model made in 64 with round rivets.

It would not be a concern if I was not planning to use the cab on my 64. I have pinks on both trucks but I do plan on going to the CHP for an inspection when the swap is done. I have been through this with a toyota and its not that bad if you have pinks on both vehicles.
I just don't know what to think of the round rivets on the 65.

We have random road side inspection every once in a while here in town so it needs to be legal or I will lose it. The last time I went through a road side inspection in 2008 I was in my 94 toyota pickup they checked all the VINs, lights, speedometer and the brakes.

I know they will install a new VIN tag after the cab swap and it does not bother me, I do not plan to sell the truck. It does concern me that the VIN rivets might not be correct so I do not want to do all the work swapping over to a useless cab.

Any help would be great.

I will try to include pictures.

Thanks,
Daniel