Fuse box started to smoke when you turned the car on? That's a little more serious than having just sat unused for 19 years as its a fire risk. Three possibilities come to mind: 1) the previous owner made modifications that had no idea what he or she was doing, created an electrical short somewhere and that's WHY it sat for 19 years before unloading their problem onto you or 2) during its slumber, Mickey, Minnie, Mortimer, Mighty, Jerry and Speedy set up housekeeping in the Supra and chewed through the insulation on a wire somewhere thus creating a short or 3) one of the relays in the fuse box has an internal short. You will only need to replace the fuses that are blown, but don't start pulling them all at random because whichever fuse(s) are blown may be your first clue where to start looking for the short. But if the fuse box continued smoking for a while, then sounds like the previous owners may have already tried putting in a higher amperage fuse than called for somewhere. As I recall, there's also a couple of fusible links in there. Make sure somebody didn't bypass them with ordinary wire.