It has to be drilled for the bigger clutch. And also, you can't interchange the flywheels on some of those engines. The 300 is balanced, the early 302 has a 28 oz weight on it, the later 302 has a 50 oz weight on it, and the 351w has a 28 oz weight.
If you have interchange questions about flywheels, starters, clutches, etc. just go to
www.partsamerica.com, and plug in all the different year vehicles with the different engines, and write down the part numbers.