WOW, NOW I understand your question. SO I downloaded your lap and P1 replay as well. When I first read your first post "and for the life of me I just can't see how to make the 1:19s happen. I finally gave up." I though you are chasing gold since I did not know times but I mean you are driving very very good. I put both lap replays in video editor so I can watch both at same time and I can tell you there is almost no difference in braking / release points between you and P1 in some of the corners. In some of the corners you are slightly overdriving it, you brake slightly later than P1 and release slightly later than P1, say 0.05 sec. What my eyes see, a pattern repeating, in most of the corners, you do actually start applying throttle earlier than P1, but you are more conservative to press the pedal since you are before the apex. and when I study speed you are almost on pair, so what happens, many corners, pattern repeating, two of you before apex, you have throttle on 30% P1 on 0% coasting, then P1 hits full 100% throttle instantly at apex.. the thing is... you pretty much do that too, maybe slightly later than P1 and speed according to numbers IS almost the same. That is THE pattern observation I could see is repeating throughout most of the corners. Should I play coach / race engineer I would tell you "few corners you are overdriving it a tiny tiny bit, brake earlier/release earlier, and we are talking 0.05 sec" and "coast a bit longer until you reach apex and then floor it". Maybe you can try that. ( I have PowerJunkie vs P1 comparison video rendered on my phone, it is something I do for myself, so I can send it to you via some wetransfer dot com or upload to YT if you want, and if you are ok that it is just that, and not a hollywood production
) Check here under two images, ten seconds in lap, check throttle application for both. Hope this helps.
