How can I convert a muffin recipe to make crumpets? If I have a recipe that I like for muffins (in the original English sense of the word, i.e. a fat disc of bread that's made from cooking a yeasted batter on a griddle in crumpet rings), what do I have to do to convert it to make crumpets instead? Looks like I need more hydration (maybe 120% instead of 100%) and to use plain flour instead of bread flour, but is there anything else?

(The muffin recipe in question is from Peter Reinhart's Artisan Bread Everyday. Except that he calls them English muffins, because he's American.)
English muffins and crumpets are very similar, the only difference being that crumpets are wetter to allow the bubbles to rise out of the side off the heat. Without seeing a specific recipe, it's hard to know exactly what adjustments to make, as some muffin recipes are also quite wet. 

If you think your muffin dough is wet enough, you could just try cooking it as crumpets. If it doesn't bubble correctly on top, try making it a little bit wetter until it works.