Lacquer remains viable as long as it's not allowed to dry out. The question that matters: "is it worth using?". Without the OEM basecoat, it's worthless; even then, a match is going to be fiendishly difficult, probably not possible. Final color depends, heavily, on application. With vintage, faded, lacquer...and it was extremely fade-prone, there's nothing of the original color left to match...using un-faded, original, paint.
I'll go further out on this limb. The Duplicolor paint Ray used is just plain better. It's far more durable than the fragile 1970-era lacquer. And, being a 3-stage, the clear topcoat imparts chip, scratch and chemical resistance that wasn't possible back-in-the-day. That clearcoat can be color-sanded & polished, if desired, without affecting the color. I understand why unopened cans of vintage, OEM, paint are commanding stupid money but, it's just that... stupid, with rare exceptions that aren't worth discussing.
As long as the prep is done right, show-quality results are possible. It's usually (not always) more difficult with rattlecans; the main tradeoff between that & 3-stage catalyzed urethane...cost/difficulty vs ultimate durability. Urethane is more durable than any other paint system. Unfortunately, it's hideously expensive, temperamental to apply properly and highly toxic, while wet.
If your frameset is 100% fade-free...and you have the vintage metallic base coat...and you have enough experience to spray a true candy color - then, you might have a good chance of getting an exact match. If you have to use a different basecoat, you'd be taking a gamble that it will be compatible with the vintage lacquer...assuming that you can source the correct basecoat in another paint system, one that's 40-50 years newer.