Best soldering practice for through hole only manufacturing
The best method for this assembly is not IR reflow.  There is a fairly cost effective method called dip soldering.  The entire assembly bench I put together is less than $900.

A simple version of this assembly method is shown in the video below:
https://www.youtube.com/watch?v=svLRtw18sXw

With all through hole parts (Assumed single staged with parts on one side), the entire board may be assembled, pre-baked, and then dipped to fill the barrels.  The temperatures chosen at each stage must be crafted based on the design and tweaked experimentally to see what gives best results without damaging the hardware.  Given my boards only house connectors, this is a simple process.