carb threaded inlet size

Hi everyone ,
Does anyone know the thread size of the inlet at the carb top for the 28PCI ? Mine has a 6AN fitting on it now, would like to go down to a 4AN, so the hose diameter matches up with the fuel pump connections better. I could take it off, but I'm running it as is this weekend, and don't want to risk causing any leakage problems so close to race weekend.

Thanks !