I've had the best luck blending original Mopar finishes with acrylic enamel. Less friendly to work with, but worth the effort IMO.
The metallics in the newer urethane paints are different and make it very difficult to get a decent match.
I've used mostly PPG's Delstar, but DuPont Centari is another option and can be used with a product called Basemaker to make it handle more like a modern basecoat. I've had the best color matches with the PPG however.

I'm assuming you're using a urethane clear over the color blend.

Feel free to PM me or email from my website contact page if you'd like.

Great looking car... wise move to save that original paint too !

Rick