Interestingly, the "maintanence note" book had some pages torn out that would have perhaps identified the original owner. There were no records, but...
So I took fuel pump/fuel sensor harness off the Van and tested each wire and connector with a meter. Everything checked out. Got those babies lookin...
Just a small update to this thread - after some months off the road and a visit with a very friendly local family-run performance shop, we found that...