Yup, I'd been to reversopumps.com early in my quest, and subsequently
contacted them as to whether gasoline was supported. They responded
quite quickly: Nope. (Actually, it says this in their FAQ section too.
But diesel would be OK.)

Meanwhile, I re-drew the "plumbing circuit" using a single
non-reversible pump and a duplex valve (e.g. an FS22-D2). It's not all
that complicated ... but the valves is very $expensive. And I'd really
like to be able to do this electrically rather than mechanically.

So I've also been researching solenoid-actuated valves, and have put in
some inquiries to several of the manufacturers as to their suitability
for gasoline. I can obviously do it with a set of four 2-way solenoid
valves, or with a pair of 3-way valves and a 2-way.

But the #1 choice would still be a reversible pump for gasoline ...
along with an on-off 2-way solenoid in series if necessary.

Thanks,
Greg