I would not have your existing plate repaired (been there, done that!).
The heliarc [TIG] welding did not hold up. The guy was a well-known
Engineer at Baldwin and told his welds had never failed. I heard the
whole plate needs to be heated and gradually cooled. There's a place
nearby that says they will guarantee the weld, but after sinking all the
time and money, if it were to crack again, that would be a disaster.
I would get another piano the same size, approximate age and same
number of notes per section. If the soundboard, bridges and pinblock
are better on the replacement piano use the whole back of it (not just
the plate). I mean, use the wooden frame, soundboard, plate, etc.,
to replace yours. It seems like a daunting task, but it's not that
hard or time-consuming a job as compared to other player piano work.
I've done this before successfully.