Chuck,
I do not know of any new tooling repop 434 TCS solenoids
As far as I know, only GM solenoids have the flat top 3 in the part number. I also believe the original electrical contacts used an amber colored sealer. Some of the NOS ones I've had didn't seem to have anything and some have a gray colored sealer.
Riveting the real to the wiring gutter is no big deal with the correct tubular rivets and correct set tool.
I would be happy to help you with that. It's also no big deal to restore the solenoids as long as the field coil is good.
Chris