In the mid '70s Electro-Voice started making the EVM series speakers (which replaced the SRO series). EV sold the name "SRO" to Kustom who had them make an OEM line of Kustom SRO speakers (15s anyway).
So, to sort of answer your question, Kustom did build cabinets with EVMs in them, but they were most likely labeled SRO.
The cabinet you show looks to be of the correct era.
Edit: If you're looking at the one on Chicago Craigslist, the ad says it was reloaded with EVM 15Ls, which suggests that they weren't original, but I'm sure it would sound great. The listing for the one at the Oxnard, CA Guitar Center (that you posted photos of) doesn't mention what type of speakers are inside (but the price is a whole lot better, even after you pay sales tax and $45 for shipping).
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Last edited by BillyB_from_LZ : 01-05-2013 at 05:09 PM.