best carb for mild 318

Rebuild it or find yourself a used holley 4160 for $40-50 and rebuild it yourself. Make sure the throttle plate bushings are not worn out. Rebuild kit is like $20-$25 with reusable gaskets. Install 65-66 primary jets, 37 squirter and a 6.5 power valve and you should be really close. Just my .02