Update:
I have purchased the '93 Legacy turbo Touring wagon 4EAT tranny, and have ordered a tranny filter and gasket kit, and new input and axle seals. The transmission number and model are: 479801 TZ102ZJ3AA-N8Issue #1:
I am still mulling over the issue of the impact of the higher stall speed of the Turbo donor TC on driveability.
I value and am taking Tapani's opinions into account -- but haven't heard anything definitive from the rest of you folks (other than to avoid 4.44 final ratio). Tom says it will work, but hasn't offered an opinion on what the impact to driveability will be. Huck just put a post out with a bunch of periods. Doesn't anyone else have any experience to share on this -- either agreeing with or disagreeing with Tapani????? 
So y'all don't have to dig to get them, here are the specs on this '94 FWD SVX -- the stock tranny had a 3.7 final ratio in the integrated front differential, and a TC stall speed of 2350-2750 RPM. The replacement tranny from the '93 legacy turbo donor has a 3.9 final ratio, and it's TC has a stall speed of 2800-3200. Should I be looking for a lower stall speed TC because the Turbo TC will make the SVX feel really sluggish at lower RPMs, or will the donor TC just make the SVX feel more "sporty" and "aggressive" like some of the Turbo models do? How about sharing some experience and opinions here?
Issue #2:
On to the next topic -- as part of this tranny swap, I am raising the transmission cooling question again....
I've read a bunch of threads on this forum, and haven't seen anything resembling a consensus being formed.
Here are the issues that seem to surface in the threads:
1. What I have read seems to indicate that extra cooling is a good thing for the most part -- especially in stop-n-go driving.
2. I've also read that flow restriction is a major problem -- especially when incorporating the stock radiator cooler in series with an external cooler. Tom favors bypassing the radiator cooler altogether. Others say to put it in series with the external cooler 1st to reduce the temp, and the stock cooler 2nd acting as a temperature regulator to keep the fluid warm but not too hot.
3. I've also read that in cooler ambient temperatures too much cooling is not a good thing as it prevents the TC lockup clutch from engaging (fluid must be at 150 degrees F or better). If the fluid temp is really low, it might not shift into 4th gear.
4. A number of folks have worried about 3/8" connectors reducing flow.
5. Some folks are using automatic t-stat valves to divert the flow to an external cooler from either the stock cooler or from simply recirculating it back into the tranny. The t-stat valves open when the fluid temp is raised up to about 160-170 degrees F). Others have expressed concern about fluid restriction using these valves, and a concern that their likely potential failure mode is to be "closed", meaning that the fluid could overheat if the valve fails and the external cooler fluid path is left out.
6. I have only seen one mention of running an external cooler in parallel with the stock radiator cooling fluid circuit. This was by Tom, stating that a customer had requested it. How did that work out?
Given all that I have read, I am leaning towards installing a smaller (10000 GVW rated) external tubing-and-fin type cooler
in parallel with the stock radiator cooling fluid circuit, and mounting it in between the condenser and radiator as Tom has suggested. It seems to me that this would eliminate the need for an additional cooling fan and would also provide some (hopefully enough) heating from the coolant in the radiator to allow the TC lockup to function in colder temps. I live in the Pacific NW (Oregon), so the temps seldom go lower than freezing -- most of the winter they stay in the high 30's to low 40's F. In the summer the daytime temps vary between the high 70's to the upper 90's, so I think additional cooling would be helpful -- especially for in-town driving. I might install a ball-valve inline in the external cooler's fluid circuit for the odd sub-freezing temperature weather that sometimes hits in the winters here.
Sooooo, what do you "experts" think about the parallel installation? Is the 10000GVW external cooler a correct size, or do you recommend something else?
Let the opinions fly!
Issue #3:
I understand that the early 4-EAT pump seals were problematic and could leak reducing the fluid flow and pressure. How hard is it to get to and change the 4-EAT pump seal? Would I need to disassemble the tranny, or is it something that can be done by just taking off the pan?
Thanks again for all your recommendations....
Philip