Plz help me to fine the adapters

[Jiney]

I heard there are adapters that will connect the A Medium format to A Lens.
But It's not easy to find the reliable adapter for me.
Please, tip me to find the one.
As I already have a 800mm lens(by KOWA), I'm looking for the adapter which can connect the one to Mamiya AFD II or III body.
If there is no ready made one, can I make it by a specialist or company?
You should recommend the other lenses to be connected to above Mamiya body.
They must be at least 300mm lenses.

 

[tirediron]

Sorry if you didn't like the answer I gave when you posted this in the equipment thread, however cross-posting is NOT considered appropriate.