Thanks for all the responses! Helpful, as always.
Kodak doesn't list separate developing times for 400TX shot at an E.I. of 200. They do list "push"-processing times, but nothing at all for "pull" or simply put, overexposure. The reference to "developing for 200 or 400" has no meaning here.
Development amount has a direct relationship to contrast of the negative. The reason "push" processing often requires longer developing times is that contrast needs to be increased to compensate for the underexposure so that there is something close to a normal range of tones on the negative, even though the shadows have been sacrificed.
For overexposure there is a lot more latitude built into the film. One stop (E.I. 200) won't make much difference; just move the densities up the curve a stop, but not to the point where the highlights should block up. If you want normal contrast, develop normally in this case.
Normal development is what you determine by testing for scenes of normal contrast and your workflow.
Many shoot Tri-X at 200 as a safety factor against underexposure or because of their preference for lower-contrast negatives.
Until '61 Trix's ISO (ok ASA) was 200, then they reduced the safety factor from about 2.2 stops to 1.2 stops.
HP3 got the same treatment.
Both changed to 400 'overnight', or if you bought a new batch of film - after an interval.
Colour did not change only mono
They said it was cause more people were using meters instead of tables or slide rules, I only had a slide rule.
Then I think they had two times for developers e.g. for condenser or diffusion enlarger cause it was fixed grade silver bromide paper.
Today if you scan you need to avoid its DMax.
Meters are easy to check you need two. Shutters more difficult all it needs is a cold day and a ribbon can snap.
The rule then was don't underexpose and overdevelop ie push.
There was only Ilford or Kodak in pharmacies.