forgot to update this thread!
I had the EPS system installed in 2018 by someone I've known for about 25+ years, who makes his living as a welder and machinist - it was supposed to be done before Carlisle 2018 but it wasn't and the work was terrible, even though he had my car for a solid 6 months!
to make a long story short, I ripped out ALL of the work he did to the electric power steering system and had the shop that did my exhaust replace all of it with either new parts or unmodified stock stuff. they're expensive for sure, but sometimes it's worth the money to have it done at a professional shop the first time around!
the one thing I stressed to the shop doing the work is that I wanted the system to be fabricated and installed in a modular way so that if the steering column position needed any adjustments or if I ever had to replace the EPS motor, it could be done easily without having to take the entire steering column out of the car and/or having to have the entire system fully fabricated again. they achieved this by using a union shaft to connect the stock prius splined shaft with the stock thunderbird DD shaft. to connect the outer tube of the prius motor to the thunderbird steering column, a v-bland flange was welded to both tubes and then a v-band clamp made the final connection.
keep in mind that the factory thunderbird column mounts in the car using 4 studs and nuts, but since the EPS motor gets installed under the dash too, there's not enough room to reuse all 4 mounting points, so the shop used the 2 studs closest to the steering wheel to mount the new set up into place and then fabbed up a mount with a heim joint to support the bottom of the steering shaft that exits the firewall...
the car did make it to Carlisle 2019. the few people who did try out the system were pretty impressed with it! sad to say though, the manual steering rack is shot and needs to be replaced as well, so I've put very little miles on the car since having the EPS system redone. I had the same guy who originally installed the EPS system replace both the inner and outer tie rods and yeah...that all needs to be ripped out and replaced too...sigh!
finally, some photos of the setup below!
mock up photos:
everything is painted up and ready for the final install: