I've got a 70 b-body wagon with a slant-6 and a 3-speed manual trans mission. I've got the pedal linkage adjusted as far out as I dare go without fear of the shaft just falling out the other side of the clutch linkage arm. The pedal is 2-3 inches from the floor board before I can feel the clutch engagement and all the way to the floor to fully disengage it. I have a new clutch in it. Could my adjusting rod be too short somehow.

I'm am not familiar what set-up you have in your wagon.
But on my old AP6 Valiant,there is a z tube(i think that's what they call it) which has the rod from the clutch pedal attached to it,then there is an adjustable rod on the bottom of it that goes back to the clutch fork.
Inside the z tube there is 2 bushes,when these flog out you can lose adjustment.

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DRIVE IT,DON'T HIDE IT

Yeah, it has the so-called Z-Bar and I will take a closer look at it and its bushings. The slop I might find from the bushings being worn wouldn't fully cause the lack of adjustment I'm missing, but every little bit I can remove will help to get a higher pedal.

I just can't crawl under it as I once could due to my lower back. I'll get the niece Kelsey out here and use her as my wrench-monkey again. She's not a bad hand at all

there is a spring clip that holds one bushing in place and keeps rod from sliding also...yes bad bushings or/and missing/broken clip can lose lots of adjustment

I'll get under it today and look. Thanks for a direction to look into

Look closely at the Z-bar welds and tube, were the arms attach.
I have seem some where the joint(s) crack and the arm starts to bend, eventually tearing itself off the tube.
DD