The Great Pumpkin - '71 Duster

FIRE, FUEL, AIR

Sounds like fuel and air are ok, what about the fire?
from your list above it doesn't sound like you verified if the spark plugs are making spark. you can use an in-line tester or do it the old fashioned way connect a loose plug to one of the wires and see if it gets spark.

you mentioned MSD, is that a box, or a coil? verify the coil is sending juice and the spark plugs are sparking to make sure that juice is getting through the wires. sometimes custom wires or tugged on wires are the invisible culprit


best of luck, let us know how it goes