I’ve done it now. There was just no way around it, that 4x12, matching my studio partner's head and 1x15, for C$80 all in. And all the speakers work. There was no choice really. Had to be done. It's been nagging at the back of my head for a month since I ran across it in the junkiest of used gear shops; a gem in a pigsty of mediocre gear in partial working order. Went back to get it yesterday.
I think we now collectively own the entire Riviera line (a Pepco, aka Pine Electronics, ‘stencil’ brand - made in Canada). I certainly can’t find any other models when I search online (though there were different versions of the 725 head, some with more knobs; no clear pics so hard to tell what’s going on there). As far as speaker cabs, I have never even heard a whisper of any Riviera other than the 1x15 (which is great, and if you ever see it grab it). The 725 amp is good too, but so much better after some tinkering (the tone stack was rebuilt on this one).
What I love most about both these cabs is that they were obviously designed for guitar/bass dual use (the 725 has separate guitar and bass inputs) in that they are MUCH larger than other similarly equipped cabs of the era. The 1x15 is perfect and I wouldn’t touch it and also it's not mine (I have seen someone on Talkbass refer to it as a Showman copy, but that's Talkbass for you, where everything has to be compared to the closest Fender model - but I think this is actually larger, certainly a different shape). Might change out the speakers in the 4x12 because they won’t handle the power of my new Sunn 1200s without getting farty (I opened her up and looked in there - 15-20 watt Marslands but nicer/better quality than most Marslands of the 70s - really nice cones and look more solid than the crappier ones Traynor was using by the end of that decade). Might stick these Marslands in the Hiwatt 4x12 my other bud is trying to sell or give the buyer the option; they do sound good with guitar. They sounded good with bass too at lower volumes - tried it with some newish solidstate Fender bass amp in the store (one of the wedge monitor shaped combos)
Replaced the rubber feet on the bottom (completely worn down to more of a rubber washer around a screw with it’s head ground down - bit of a pain to get off) and glued down some ripped flaps of tolex. Gotta find a strap handle for the right side there, and then maybe some castors (side mount for a tilt n roll) cause it’s a beast - not that heavy, but large and awkward to carry - it’s actually bigger than the Sunn offset style 4x12).
To give an idea re the scale of this beast, it is 30 x 41 x 12" (vs a standard geetar 4x12 which is 30 x 31 x 13). The amp head is tiny.