I always start w/this guys birria stew, then riff off of the second link where he makes more broth for tacos. Not as "authentic" since it uses short rib and chuck. Still the best I've ever tasted by a long shot. My wife and I try birria every time it is on a menu and they always disappoint.
https://www.allrecipes.com/recipe/282066/beef-birria/I don't spice the meat 12 hours in advance. I cut and it, add the spice then, then move on to all of the veggie steps. For the dried chilis I've never used only 7 guajillos. I typically riff and do something like 4 guajillos, 2 pasilla, and 1 ancho.
For the consume/tacos (link 2) iI really just add water/broth to the original liquid, cook it down a bit, add more spice to taste, etc. Let it cook down a bit, continuing to scrape down the frond. If there's any oil i skim it and add to the saved oil from the first link.
https://www.allrecipes.com/recipe/282114/beef-birria-queso-tacos-with-consome/It's critical to skim as much oil as possible. That's used to get the nice orange crisp on the taco shells.
Note: I always used the spices as he calls them out, then add more during the consume phase. Adding more is truly just dash, stir, taste. I'll add pepper, cumin, any of the random chili powders I buy at Pendrey's in Fort Worth, etc. Always do it slow and give it a bit to incorporate before adding more. I try not to add too much salt until the very end since that will strengthen as the consume simmers.