It's an intriguing match-up, what Thor being the god of thunder, and Adam getting his power from lightning. I'm not sure Thor's lightning would have any special effect on Adam though, beyond what it can do by virtue of it's sheer power. As far as I know, Adam's powers are only activated/deactivated by Shazam bolts, not lightning from other sources. In DC VS. MARVEL, we saw that Thor could use Mjolnir to intercept a Shazam bolt, but I don't see him getting that opportunity against Adam, since Adam isn't in the habit of reverting to human form midfight (Billy only did so due to the rules stipulated by The Brothers).
So more likely than not, this'd be straight contest of power vs. power. And Thor could still win on those terms, but it'd be near 50/50 fight IMO. On the off-chance that Thor did manage to manipulate Adam's powers in some way though, that'd obviously tip the scales decidedly in his favour.
