Ambassador, Bishop, Haggler, Horn of Plenty, Oracle, Pirate Ship, Sea Hag, Secret Chamber, Tactician, and Torturer
Hmm, so assume we ignore Ambassador. What we want is a deck that still works when it's bloated. You don't want to curse, as these only come back, so Torturer and Sea Hag are out. You don't want Pirate Ship as you won't have many Coppers to hit. You don't want HoP as there is no engine to build. You don't want Secret Chamber because there is no reason for it to work. Tactician-SC needs to draw a card, which you don't have here. OK, maybe you pick one up on 5/2, but it's not the center of your plan.
You don't want Ambassador because that's what we assumed.
Remain Bishop, Haggler, Oracle, Tactician...
Bishoph-Haggler-BM seems the most promising for me here. Maybe with Tactician, I don't know. If with Tactician one can maybe again think at HoP, in Tactician-turns it should get up to $6 at least, but $8 is impossible here. Bishops don't help your opponent when they are Ambassadoring.
So I think from 5/2, start Haggler/nothing, get 2 Bishops fastly, more later depending on the draw, and try BigMoney. There's no engine for the Ambassador anyway, but it could go for Pirate Ships after it trashed down, which will probably be quite powerfull against an Ambassador-flooded BigMoney. Without the PS, I would be quite confident in Haggler-Bishop-BM from 5/2 against Ambassador, but these are a bit frightening.