Finally got a few minutes to start looking over the car in a bit more detail, though I haven't taken anything apart yet. Having some experience with this gen Celica and having read the three Seamus builds gave me a starting place to begin looking for rust. Good news is that there's minimal visible anywhere. Looks like someone sprayed the heck out of this thing early or at the beginning of its life with loads of wax: Inner panels in front of and behind the rear wheels show no signs of rust on either side:
I did find that the power antenna was aftermarket, but it works at least.
Spare tire well is pretty clean, but the main drain plug might have a touch of rust around it, I'll have to examine more.
Looks like a little surface rust on the bottom of the panel between the rear bumper and gas tank.
Hatch is pretty clean with no rust on the bottom or inside any holes visible from the inside. There is some rust at the edge of the weatherstripping between the hatch and the right side bottom edge of the spoiler. I'll have to remove that to see how bad it really is.
At the hatch hinges, there's a tinge of discoloration at the seam between the hatch area and roof skin. Definitely something to look into.
Popped the rear shock caps and didn't see a speck of anything inside either side.
Both doors look clean without a speck on them.
Underneath and undercoated wheel wells all look really clean. Stupid factory jack points/pinch welds are all bent up, but no rust at least.
Sunroof has one spot on the leading edge that'd been touched up at some point. I'll have to look deeper into the sunroof at some point.
The hood is clean except for one small spot near the latch.
Windshield cowling area looks spotless
Under the battery tray looks clean from what I can see, and much of the underside of the hood and inner fenders were also sprayed in wax. I haven't gotten to review the lower radiator support yet.
The worst rust I've found so far is at the leading of the PS fender, just aft of the parking light. Looks like contact occurred at some point, and even this is minor.
So far, all of these areas were only examined where easily visible without much disassembly, but it's encouraging. Since the car is surprisingly clean, I'll likely be following Seamus instructions and sealing up any and all seams as possible to minimize future issues. As time allows, I'll dig deeper, but in the meantime, I'm making parts and to-do lists for the car. Most are generic for a car that's been sitting for a bit. Fluid changes, top end gaskets/seals, timing belt, hoses, belts, tires, battery, etc. This thing leaks some serious oil from the cam towers, but the timing belt/covers are dry, even though the timing belt seems to have too much play to me.
More pictures to come over the weekend.