Line a 10-inch deep-dish pie plate with half of pastry; chill remaining pastry.
Sprinkle salt, pepper, mace, nutmeg, and cloves over lamb cubes. Place lamb cubes in a medium Dutch oven; cover with water, and simmer 2 hours or until lamb is tender. Drain lamb, reserving broth. Set lamb and broth aside.
Cover sweetbreads with cold water, and let soak 1 hour; drain. Place in a Dutch oven, and cover with fresh cold water. Cover and simmer 1 hour. Drain well, and chop; set aside.
Drain oysters, reserving 1/3 cup liquid. Cover oysters with water, and cook over medium heat 8 to 10 minutes or until edges of oysters curl; set aside.
Add reserved lamb broth to oyster liquid to equal 2 cups; discard remaining lamb broth.
Melt 1/4 cup butter in a heavy saucepan over low heat; add flour, stirring until smooth. Cook 1 minute, stirring constantly. Gradually add lamb broth mixture. Cook over medium heat, stirring constantly, until thickened and bubbly. Remove from heat.
Combine wine and egg yolk, stirring until well blended. Slowly add wine mixture to creamed broth mixture, stirring gently to form a sauce.
Combine lamb, sweetbreads, oysters, and sauce in a large mixing bowl; stir well. Spoon mixture evenly into pastry shell, and dot with remaining 2 tablespoons butter. Cover with top crust, and slit in several places to allow steam to escape; seal and flute edges. Cover edges of pie with aluminum foil, and bake at 350° for 1 hour and 10 minutes.