As a starting point, I offer the following kingdom:
Fairgrounds, Duke, Silk Road, Vineyard, Gardens, Feodum,
Kings Court, Scheme, Bridge, Workers Village.
Colony/Platinum in game
Assumptions: You are going to buy out the all of the cards in the kingdom. (Including copper, silver, gold ... but not curses)
How: Buy out all of the cards in all of the piles ... leaving one card in each pile only. On the last turn buy all the remaining cards
Mechansim: The kings court, scheme, bridge, workers village. Kings court bridge makes cards free. Kings court scheme gives you a little draw and allows you to top deck everything ... so once the combo gets going, it works in perpetuity. Workers village is for +buy to make sure that you have enough buys to buy everything out - but this could probably be optimized. If you kings court 9 bridges that gives you 28 buys ....
VP choice:
Fairgrounds = 8 per fairground on this kingdom (20 unique cards) = 64 points
Duke = 8 per duke = 64 points
Silk road = 7 victory piles = (7*
= 56 victory cards = 14 points per silk road = 112 points
feodeom = 60 silvers / 3 = 20 points per feodum = 160 points
Gardens = over 250 cards = 25 points per garden = 200 points
Vineyard = (40 action cards / 3 ) = 13 per action card = 104
estate+duchy+province+colony = 22 per set = 176 in total
So all together this calculation is close to 900.
Add the two landmarks that add the most points in, easily over 900 points
* notes - castles disallowed because they have victory tokens in 2 of the castles. Assumed black market is out - or fairgound points would go crazy high.