The “K889” at the end of the 12 character HIN indicates that the boat was certified (built) in November of 1988 for sale in the 1989 model year. The first three characters are the manufacturer’s identification code which should be “MAD” not “VAD” as Kim said. The “EX” is a model code number that MRC used for Explorer models. The “788” is the actual serial number. The “-K” at the end is not actually part of the HIN but was appended to the end of the HIN by MRC on their Kevlar models.
I would give the hull a good washing with hot water and Dawn dishwashing detergent and see what it looks like. If there is still a lot of oxidation then I would wet sand it following ptickner’s advice. I have also had very good results using 3M Finesse It II and a low speed automotive buffer. Apply the glaze to small areas at a time and don’t let it dry on for very long before buffing.
The oil versus bright finish debate has gone on for a long time and it is largely a matter of individual preference. I have used both. I can tell you that “penetrating oil” really doesn’t penetrate ash more than about a molecule deep. It is basically a surface finish as is a bright finish consisting of varnish or polyurethane.
I prefer a bright finish on canoes that are going to be used primarily on flat water where sudden maneuvers involving possible pries off the gunwale or contact of the gunwales with rocks is unlikely. On whitewater canoes I prefer oil on the gunwales but will often use a bright finish on thwarts, yokes, and seat frames which are better protected. If you want to bright finish your seat frames make sure to do so before recaning. The cane was going to break no matter what you did by the way.
A bright finish lasts a lot longer and does not mildew but looks like crap if it gets too scratched up. If your usage makes it likely that the wood trim will be subject to scratches, oil may be preferable. Oil is much easier to apply, but requires you to keep after it. How often you need to reoil will depend on your use, climate, and storage, but anticipate having to reapply it a couple times a year. Everybody thinks that will be no problem, but many fail to do so.
My preferred bright finish has become two or three thin coats of a very non-viscous penetrating epoxy like System Three Clear Coat followed by about three coats of varnish like Epiphanes or Petitt Z-Spar Captain’s varnish with wet sanding with 1500 grit paper in between coats. A complete finish job like that will take a lot longer than applying a few coats of oil, but will last a lot longer.
Whatever finishing method you use, take out the seat frames, seat hangers, yoke, and carry handles and make sure you finish the cut ends. These cut surfaces often get ignored at the factory and the end grain of ash loves to soak up water leading to rot. You can apply oil or varnish in the screw holes in the wood using a pipe cleaner. If you get very ambitious, you can remove the gunwales and treat the inside hidden faces of the outwales and inwales with penetrating epoxy. But if you want to treat the outside faces with oil, don’t get any epoxy on those surfaces or you will have to sand it off before you oil.
That should be a very nice canoe. I have a Kevlar Explorer that dates back to around 1983 when MRC still used non-radiused outwales on their wood trimmed boats.