no easy way, but you might be able to save some work and rebuild it quickly.
once you import your assets and set up your comp to match the v7 one, select a layer, hit uu, select the keyframes (or I bars for those parameters that are not default) hit copy, then paste it into a text doc. change ae7 to ae6, copy all, then select the corresponding layer in ae6 and paste.
depeding on your project, this could be a real timesaver
who is that masked man…
https://www.exposedideas.com/