Texaco Tanker Chrome - How to build and save the chrome around seams?

It depends on how much touch up you need on seams.  Just be very careful cutting away parts from sprue, and in preparing for glue. If only a few small spots are bad, you can carefully touch up with a very bright silver such as Floquil or such.

If there is an extensive large area, then you'll be forced to refinish with Alclad, as fox says.

Just taking a guess that the top seam is under the walkway on top of the tank and the bottom seam is hidden under the rails. If not, just seal up the seams with putty and use Alclad on the tank.

Jim