Looks like US Car Tool has Early A sub-frame ties available. Oh, I know they are expensive for us budget minded builders but they look cool and I like the concept. toolmanmike
http://store.uscartool.com/63-66-Mopar-A-Body-Frame-Connectors_p_41.html
http://store.uscartool.com/63-66-Mopar-A-Body-Frame-Connectors_p_41.html