Well after taking a break from this project since October I finally got going again. I found a set of used ST165 shifter cables on eBay over the winter and installed them this weekend. Before I put them in I compared to the shifter cables I was having trouble with. Very obviously I installed one correct cable and one from likely a ST202 Celica. That was an idiotic thing to do on an otherwise trouble free swap.
Now with the correct shifter cables in and an upgraded shifter spherical bushing (PRIMEMR2) it feels nice and tight. Put the interior back together.
Next step is bleed the clutch, adjust the gas pedal to work with the ST205 accelerator cable, and clean up the misc wiring and modules in the engine bay. Then take it for it's first drive in 20 years!!!!