Bigger Port bigger valve and they are open chamber.
I think the only thing the 302 head and the 308 head have in common is they both bolt onto the small block Mopar and they both came out at about the same time.
The 308 head with its open chamber far out preforms the 302 head with its closed chamber.
To edit this, both heads also have the huge push rod hole for use with the roller cam Motors.
