I think the lid your using is the smaller diameter lid. They made em in a larger diameter that was used painted black on slant 6 and chrome on 273. I dont think your going to get enough airflow if yours is the smaller 6 only lid. I can measure mine across and get you a dimension. If you cannot find one, i may have a spare of the lid you need. Heres pix of mine on workbench. It may more of the carb because may be a larger diameter.
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