I was at the local Pull-a-part yesterday and decided to pull some struts and compare them. The pic below show an '84 Tercel4wd strut, next to a '91 Tercel strut, and a '91 Corolla DX strut. it looks like the T4wd strut is unique. They all have similar lower mounts, which should bolt up to the Tecel4wd hub mount, but both the length and diameter of the spring is different on the other struts.
The Corolla strut has a larger dia spring, but it appears to be the same overall length. The upper mount is different too, the Corolla uses three bolts in an even triangular pattern. Thought the upper mount might just swap out with the Tercel ones. If the larger diameter spring is not going to cause clearance issues it looks like it might adapt to the T4wd. The corolla is a heavier car so should have a stiffer spring and shock. All appear to have the same strut diameter, so I am going to double check what is in my Corolla All-trac since I remember it being larger. All also have the spring seats appear in similar location on the strut (the '91 Tercel is a little lower), but they are all slightly different shape. the '91 Tercel strut is shorter likely so they can lower the hood line on the newer Tercels.
The '84 Tercel4wd strut is on top, the '91 Tercel strut in the middle, and the '91 Corolla strut on the bottom. The T4wd and Corolla strut appear to have the same length and travel. The '91 Tercel strut would fit, but it would lower the car, it would also be a bit stiffer spring too.
This is the top mounts, The '84 T4wd is on the right, the center '91 Tercel, and the '91 Corolla on the left. The upper mount used four bolts on the '91 Tercel, which would likely fit the T4wd if you pop out the plastic plug in the 4th hole in the top of the strut tower. To use the Corolla mount you would either have to drill new holes in our strut tower, or see if you can swap out the T4wd top mount. Either way it appears the Corolla strut is a good candidate for an low cost upgraded strut for the Tercel4wd.
The Camry strut is similar but also much larger and heavier, not a good candidate for the Tercel4wd, but I will have a look at it next time I go. The spring gets stiffer of course if the wire size is larger, but it gets softer with more coils and larger diameter spring. So the '91 Tercel spring should be stiffer since the wire dia and coil dia. is the same as the T4wd, but with few coils. The Corolla spring uses heavier wire, and is larger dia, but also has few coils than the Tercel4wd, so it should be stiffer too.