Bruce, Facebook caches results, so you aren’t going to see a change immediately, if you’re just trying to share the post normally.
The tool you’d want is this one:
(and I’m cracking up that THAT page doesn’t have all it’s og tags set!)
Be sure to tell it to rescrape (an option on the results page).
I think the “style tag too big” idea has some merit - and it’d be easy to test. Drop everything in that style tag into a css file, and replace with a line that loads that css.
(Alternately, move the partial that contains the css to below ghost_head, but note that this will mean your code injection header will get applied before most of the css loads, so the theme’s css will overwrite your code injection css if you don’t have enough specificity.)