On the passenger side of the SBC the upper water pump bolt hole aligns with the fuel pump rod, often this hole is used with a longer bolt to hold the rod in place when changing the fuel pump. If this longer bolt is left in place after changing the fuel pump it can cause noise such as you are encountering. And, in a worst case scenario it can cause damage to the cam’s fuel pump lobe. Loosen this bolt, if the noise goes away replace the bolt with a shorter bolt.