There is a braided ground wire from the battery to the frame.
You might want another braided ground wire from the frame to the clutch housing or a starter bolt.
Make sure all the contact points are clean and shiny. I coat all sides of the contact surfaces with an anti-oxidant copper impregnated "grease".
antioxidant "greases"I use this Permatex Product.NAPA and other auto stores have their own similar product.