Are you looking for ignition parts? Like coils, points and condensers? If so, then yes, parts from a 1967 9.8 will fit the 1964 20. You can also get points and condensers new, right here on i-boats (part number 18-5007). And I believe the coil, #[FONT=arial, sans-serif]18-5178, will work for you, too.[/FONT]
If you're talking about an electric start set-up, then no, they won't work.