You meet the criteria, so you obviously ‘stand a chance’.
On the practical front:
=As @Conformist1688 pointed out on your other thread, Oxford Hx + Econ will require both the TSA & the HAT, so take a look at those. See if there is a test site nearby; if not you will either have to travel or your school will have to become a test site- doable, but it can take a time.
=Oxford will also want to see a paper written for history class, so take a look at what you have now and what you might have by November.
=Hx + Econ is a tiny course at Oxford- less than 20 places iirc. IF you got invited to interview you might be asked if you would accept straight Hx- something to think about. Joint courses are typically harder admits at Oxford, b/c tutors from each department have to agree on each candidate
=LSE takes very very few US undergrads. Based on a FOI request (helpfully posted by another recent CC poster), in the 2019 intake, out of 99 US applicants across the various Econ courses they accepted 5: 1/10 Econ Hx and 4/60 straight Econ applicants.
=imo, UCL is a likely admit
=Be aware that any offer you might get (from any of them) will be for based on your achieved and scheduled APs, and they get to choose which exams. So, you may have enough APs for an unconditional offer, and they can still give you a conditional offer that includes any of your Sr year APs…
=There is info on both the UCAS & Oxford websites on writing LoRs- suggest getting that info to your recommender (n.b., references to ‘contextual’ applicants don’t apply to you). Be aware that if your referee predicts a score less than 5 for any course that the unis could consider relevant that could be a deal breaker- but equally, if a 5 is predicted, it can be part of a conditional offer.
=You get 5 choices for the price of 1 (the same exact app goes to everybody), so you might consider adding others such as Durham (collegiate uni, like Oxbridge) and St Andrews (Scotland, so 4 years).
=Imo the 1480 overrides the 1280. I gather you know that LSE doesn’t consider SAT, and nobody else in the UK much respects it: they set a score as a marker or gateway, but once you’ve ticked the box they move on to APs.
On the more qualitative front:
= All the unis see the same essay. Be sure to marinate in the available info, to both be sure of your choices and so that your PS demonstrates that you & each course are a good fit.
=Use your research skills: there is a LOT of info online, down to individual module descriptions. Be sure to mine YouTube, etc for both uni & student input.
=If you don’t already read the Economist regularly, start doing so now- all of it, not just the Econ section!
=Read, read, read. Scan the pre-reading lists that are typically buried on the website for each course. You don’t have to read any/all of them, but you should get a sense of the type of reading that you will be expected to do (and that many of your peers will have done). You may happily discover, as my HisPol collegekid did, that you have already read quite a few of the books, either for school, or just b/c of a love of the subject. IMO, that is a good sign 