Weigh or lightly spoon flours into dry measuring cups; level with a knife. Combine flours and next 6 ingredients (through cloves), stirring with a whisk.
Place sugar, pumpkin, and oil in a large bowl; beat with a mixer at medium speed until well blended. Add buttermilk, vanilla, and eggs; beat until well combined. Add flour mixture; beat at low speed just until combined.
Place chocolate chips in a medium, microwave-safe bowl. Microwave at HIGH 45 seconds or until chocolate melts, stirring after 30 seconds. Add 1 cup batter and cocoa to melted chocolate; stir well to combine.
Spoon half of pumpkin batter into a 9 x 5–inch loaf pan lined with parchment paper; dollop half of chocolate batter on top. Spoon remaining pumpkin batter over chocolate batter; dollop with remaining chocolate batter. Swirl batters together using a knife. Bake at 350°F for 1 hour or until a wooden pick inserted in center of loaf comes out almost clean. Cool 10 minutes in pan on a wire rack. Remove loaf from pan; cool on rack.
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