Catfish - that's an awesome suggestion about the glove box. Unfortunately a prior owner must have broken the glove box door and did a junk yard find at some point as the VIN doesn't match the dash.
Oregon is picky about the VIN for whatever reason. The DMV actually charges $7 for the inspection. If they don't find a 2nd one in the standard location, you get some grief.
A saving grace I may have is that this van was registered in Oregon as recently as 2018 before it was sold to the buyer in Idaho who had it re-titled there. Now I'm bringing it back to Oregon. I'm going to suggest to DMV this week that they had previously titled it and the VIN, description and prior owner match. I also have paperwork from 2012 where the Oregon owner had tires replaced that includes the Oregon licence plate number, and a transmission rebuild that includes the last 6 digits of the VIN. Finally, the original conversion company from 1994 kept the "incomplete vehicle" booklet from GM. I have a copy of it and it includes the same exact VIN number as this particular vehicle.
I'm hoping that any of these are good enough. It all comes down to how picky the inspector chooses to be.
Still, I'd love to find out if there is a VIN on a frame rail or the like. The engine is original, but I expect it will have the engine casting #, not the VIN. I've not attempted to see if it is inscribed, or part of it, on the motor mounts.
Reference about Oregon if curious:
https://www.oregon.gov/odot/dmv/pages/vehicle/vininspection.aspx