I assume that your '70 chassis is currently non-operative. When you go to revive the registration on it, they may require an inspection of it to ensure that all the number match, and that it isn't, oh, let's just say a '78 that you're trying to register as a '70 in order to avoid a smog check. I don't know how they do that, but I know that in California with their draconian smog laws, they've seen it all and will probably be wise to slight-of-hand.
I'm not making any judgments here, just letting you know that you may have to present it, tell the story of it, and sign an affadavit that it is what you say it is.
I'm not making any judgments here, just letting you know that you may have to present it, tell the story of it, and sign an affadavit that it is what you say it is.