For Astrophotographer and Stray Cat
A few comments
In a western world fixed wing aircraft, the copilot's window is always on the right.
When he said he was flying west, unless he states a specific heading, he is giving a general heading, something + or - 20 degrees or so. I know that makes your job harder. The error circle just got bigger.
Ground speed is TAS corrected for wind. In this case GS is what you are wanting to use for positions, direction and time across the ground. For distances from aircraft to aircraft at the same altitude and wind, Indicated AS would be satisfactory.
Weather conditions 2 hours away from the incident would be getting iffy for accuracy. Unless there was a front close by, the wind would be fairly accurate. (what accurate means, I don't know; for my purposes, it didn't matter.)
Unless the pilot specifically stated, for some esoteric reason, that he was using true headings, he was using mag, that is just the way a pilot thinks.
I know this makes things more complicated, and it gets complicated pretty fast. You saw on the other site, one of the posters getting totally confused. He was actually making it more complicated than necessary, as well as making the wrong assumptions.
For Stray Cat
Your straight climb would be correct unless there would be some weird airspace restrictions. I also found a rate of climb number for a Super Connie of 1600 fps. Considering the difference in models, using 1400 fps should put you in the ball park and probably with less error than the rest of the story. You should now be able to calculate time and distance to climb.
PD