1973-4 was about the time I upgraded my dorm system to something suitable for a real apartment. Dorm system from 1970 was Nikko (a tiny TRM-40B that was promptly modded by an EE roommate) and SF Radio speakers. Replacement was an Altec (not in your collection!) compact and EPI-100 (in your list!) speakers - still have the speakers, working great after a couple of rebuilds (most recently with Human Speakers components). A TEAC cassette deck showed up soon after (low-end bright version of what's in your ad; long gone). Somehow, after trying several other speakers and receivers/amps over the years, I keep going back to the EPIs for really good sound whatever I'm driving them with.
Is it worth fixing a pair of Radio Shack Mach 3's (much later than these ads) with disintegrated foam around the woofers?