They were 95 amps each from the factory in Dodges although a little overkill on rewiring wouldn't hurt.
Service manual excerpt:
OPERATION
The air heater elements are used to heat incoming
air to the intake manifold. This is done to help
engine starting and improve driveability with cool or
cold outside temperatures.
Electrical supply for the 2 air heater elements is
controlled by the Engine Control Module (ECM)
through the 2 air heater relays. Refer to Intake Manifold
Air Heater Relays for more information.
Two heavy-duty cables connect the 2 air heater elements
to the 2 air heater relays. Each of these cables
will supply approximately 95 amps at 12 volts to an
individual heating element within the heater block
assembly.
Refer to the Powertrain Diagnostic Procedures
manual for electrical operation and complete description
of the intake heaters, including pre-heat and
post-heat cycles.
