If you have the Wieand pump compare it to the old cast iron unit.
You will see that the bypass in the iron casting and an undrilled portion of the casting in the Wieand.
Take a 3/8" diameter drill bit and drill it out to match the iron unit.
You definately want the bypass in the Pantera. A Mustang will survive without it. The Pantera won't.
Been there done that.
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