A copper clad aluminum center conductor is the standard in the industry for RG-8 size low loss cable such as JEFA Tech Low Loss 400. CCA is preferred due to the lower cost and lower weight vs solid copper. All major manufacturers use copper clad aluminum center cores for this type of cable. This includes Times Microwave LMR-400 and Commscope WBC-400 among other major brands.
RF energy travels on the outside skin of the conductor, not the center, so it will be on the copper part of the center conductor and not the aluminum. This is known as “skin effect”. There are no performance advantages to having a solid copper center conductor when using a solid core cable.