Forbidden Orchard has made appearances in Grim Long decks in the past but its mana base was never based around it.
What type of combo deck are you working on? What's the kill? How many colors are involved? If you are working within a price or proxy range then maybe combo isn't the best road to victory. There are no optimal budget combo decks in Vintage. The closest might be 2-Land Belcher for Legacy.
Have you tried using the
Vintage Deck Database over on Star City Games to search for decks using certain card(s)?
Both this and a
previous post of yours are really lacking in content and asking the reader to do a lot of the initial legwork for you with very little to go on. That's not really best way to go about doing things. Particularly here. We don't mind helping out newer players but try to meet us half way. Read through these boards to get a better idea of what's already out there and what it is you'd like to do/say. Then post something with a little more content and direction.
I hope this helps.