After four years, I finally gave up on taking the heater matrix in to be repaired and spent some time searching for a "close enough match to fit” into the Kodiak in the Series. Turns out, the matrix from a Bronco II looks a bit like the original. Other than blocking the sides with some stiff closed cell foam, and making sure the pipes are pushed through long enough, I didn’t have to do any kind of modification.
With the water pump showing 161 degrees, the matrix inside the cab showed 140 degrees. The flow is a bit better than what I get in the Defender, and the temps I get out of the Defender vents is only 94 degrees even when the engine is at 190.
I may be driving the soft top series to stay warm.