Firstly, you need to get 4 BA flights where you need a TP qualifying fare (so the cheapest economy ticket will not work but any CW ticket would count). LHR-LAX return would be 2 fares and 240TP. I can only guess you have a European CE flight as well as that would give you 80TP making 320TP.

KUP/YUP flights that are over 2,000 miles in First earn 180 TP one way/360 TP return - so that means a direct flight LAX/SFO/LAS to JFK/EWR/MIA. LAX to LAS would only gain you 60TP one way because it is under 2000 miles. LAX-ORD-JFK would get you 120TP one way because both flight segments are less than 2000 miles each.

Do not get too hung up over YUP/KUP fares that would be great if you doing trans-continental flights which you are not. Just go onto expedia and look up F fares on AA. If you find that there are reasonable fares then go for it. Four AA domestics flights (ie 2 returns) would get you 60TP x 4 = 240TP. If the fare appears reasonable; it is probably a KUP fare in any case,

That would leave you 20TPs short of Silver; so one full fare economy should do it.