Oh geezz… you have a “snowbird” tach.
What’s wrong with Toyota’s ignition system?
Toyota parts do everything special.
The only “upgrade” I do to ignition is metal core spark plug wires, iridium spark plugs, with Echlin cap & rotor.
With a 1985 Toyota pickup, everything is most likely “breaking down slowly”.
Except the ignitor.... they usually work or not work.