Wanted to follow up on this and reiterate two of my points from above (bolded). The ad was a scam - and a very well executed one. Despite the seller seeming incredibly knowledgeable about pre-moon Speedies, as well as that particular one, I found a picture on Instagram of another 145.012 in Europe that was identical (even down to lume markings and patterns). Obviously, no two dials age in the same exact way, so I told him to send me a dated picture with the watch next to it. That picture never arrived and he went radio silent after responding within minutes to everything else. Thankfully, as soon as I saw the IG picture, I filed a claim with PayPal as well and it was resolved yesterday (with the funds wired back into my account).
So the main takeaways - a) if you're buying from Mexico, ask for a dated picture with the watch, b)
always use PayPal, and c) if your antenna is up from the get-go, don't let the bargain price taint your judgement. I knew there was probably a 50% chance that it was too good to be true, and thankfully it didn't cost me anything to find out for sure.
Finally - here are pictures of the Speedy. Vision Vintage Watches is the actual owner in the EU, so don't buy one with these same markings unless it's from him!