Lucky Number 7 is doable from my set. Using Rifle ammo (not Sniper Rifle) to sell let’s you get 7 and 1 in the final digit.
Im having the same issue with Lucky#7 using slot#8 ( I was able to get the other two trophies associated with this slot ) Im usually pretty good with figuring out weird saves, but im stumped. what do you mean by " 1 in the final digit" ? slot 8 has max Lei, so im assuming that you need to have 777 , 7,777, etc in the dukes purse ?
ive also tried your copy over save slot method, and I keep getting a load error ??? this is what I did, please let me know if im doing it wrong.
1. Loaded my original play through ( saved before placing Giants chalice )
2. used typewriter & re-saved to slot 8
3. copied your resigned slot 8 from usb ( kept my OG sys.dat ) = load error
repeated steps & used your sys.dat = trophy doesn't pop
BT