yeah, as someone who really F'd that up before, Try "advancing" all your ignition wires about 180 degrees. The "pops" are a common symptom of having the whole setup reverse. I kept getting it wrong because I set the timing to the exhaust stroke not the compression stroke. One of the volvo gurus suggested that you pull the #1 spark (you'd be doing this anyway to set static timing) and then crank the engine (by hand) with your thumb over the #1 spark plug hole until you feel air push your thumb away. That's true #1 TDC.

If that is not the problem and you get a good spark when you set your static timing, then take the carbs set to a basic startup setting. Mixture setting about 12 flats (two complete turns) down from the top-most setting, and the throttle screws adjusted about 3 turns down.

If that fails, open up the float chambers and fill them manually. You should be able to start and run the motor for a couple minutes without any fuel at all from the tank.

Try to narrow the issue down by confirming each part of the ignition system Fuel, Compression, Spark

You are in the land of volvos and knowledgeable mechanics ought to be hanging from the trees out there.