Yup, the thinner head gaskets and closed chamber heads hopefully raise the cr to somewhere around the 9's. It was a toss up with me between the 340 cam and the xe268.
From what I've seen you won't see 9:1. If memory serves I had my 273 closed chamber heads milled 15 and used the Mr Gasket thin head gaskets, mine came out to about 8.6, but good enough for what it is :) I think the 302 heads might have a tiny bit smaller combustion chamber but I'd use whichever was found at the right price.