I don't think you will ever find a X or J head with 63 or 65 cc, as delivered from the factory they were all in the 68-72 range with the vast majority around 72. The closed chamber magnum head will measure out at 64cc.
FWIW, all open chamber 340/360 heads right up to the mid 80's 308 head have the same chamber and port design. The only difference is manufacturing variations.