Success! What an improvement! Thanks for the guidance everyone (and for all the old forum posts!). I'm sure I've got lots of tweaking and whatnot ahead, but she fired up which is the important bit.

A few notes for anyone finding this post in the future - I put a K614 kit on an 1986 2.0 with an automatic transmission and the mechanical fuel pump.

* I kept the mechanical pump and added a Mr. Gasket fuel pressure regulator. I'll switch to electric when/if this pump dies, but I figured I'd tackle one thing at a time. The lower output on the mechanical pump went to the carb (via the regulator). The upper output on the pump went to the return line, which was previously connected to the Mikuni and goes to a hard line, closer to the firewall than the inlet from the tank.
* My mechanical pump outlets were 1/4", the inlet on the pump is 5/16. I adapted the lines at the pressure regulator.
* I transferred the kick down bracket from the Mikuni to the new carb. The K614 kit does come with a bracket as well, which you could rig to the kick down. This seemed a little cleaner. I had to grind down the bracket to fit. Here's a photo
* Don't disconnect the temperature sensor and then wonder why your gauge is dead

Finished Product