A 307 Chevy is 3.875 bore you can go 60 over max if the block is clean not rusted out water jackets . This will make it a 3.935 bore 316ci . Or if this engine is a test engine only . And if the bore looks good rering it as a 307 . Install a 450+ lift cam and a high rise intake with a Holley or AFB 4BBL . Also use an HEI easy 1 wire 12volt set up . For exhaust use headers mounted up in the air like boats run them . Chrome valve covers and air cleaner . Paint it Chevy orange and your ready for a show . One more thing a lot of these parts you can buy cheap from your local Craigs list . I also have a test stand go to my photos . COOL