“Head Over Heels”.  Doesn’t really make sense, does it?  That’s where your head is supposed to be.  I always assume it’s like the other old saying that’s used backward: “You can’t have your cake and eat it, too.”  Probably not designed with modern American English in mind.  Currant parlance would have it “You can’t EAT your cake, and HAVE it, too.”  Y’know, ’cause it’d be gone.  So, “Head Over Heels” ought to be “Heels Over Head”.

Or, you could ignore the problem and use P.G. Wodehouse’s version, “Base Over Apex.”

I like that one.