Modification of K-member idler arm mount advice

That looks more like it! I'm glad you had someone who could come put hands on. Over the internet is difficult at best.
It was lucky to have someone who could go hands on! For stuff like this it can for sure be difficult to explain in text.
Are you going to move the motor mount, too? Or just buy a conversion mount?
I'm doing an engine swap once the car is straightened so I figure I can just weld in something new and remove the old mount down the line.

None of these cars were perfect from the factory. I bet what you've done is more than adequate. Nice work!
After measuring we started to think just that, it might actually be better than factory..!

It may be apples and oranges but here are a couple pictures of my '70 Charger. I have standard length idler and Pitman arms and the center link isn't exactly perfectly perpendicular with the engine or car. It aligned great, tracks straight and has zero ill manners.

Not sure is this helps but I know that I get the impression that the cars were all supposed to be square and even everywhere but some stuff was just "imperfect" even when built to spec.
That is interesting and certainly reassuring. If you take the quality of the welds on the k member you into account then there are probably a few other imperfections on these cars.