Get your garage to check the dizzy cap and rotor arm, especially the carbon brush in the dizzy cap. Amazingly i've known these cars still run without a carbon brush but starting was a problem!
It sound like they haven't done this yet or assumed they don't need to because a spark is reaching the plugs. However it's entirely possible that the spark they are seeing with the plug out is ok but not strong enough to fire when under compression.
In free air (in other words about 15psi pressure or 1 atmosphere) 25kV will happily jump a half-inch gap. Increase the pressure ten-fold to 150psi (typical compression pressure) and the same spark will struggle to jump 1/32" so might pay to check the plug gaps as well - should be 0.65 - 0.7mm (0.025 - 0.028") and maybe even stick a new set of plugs in it - correctly gapped of course!
While checking the ignition side of things, check the ignition amplifier module too, sometimes a failing one will go weak and deliver a spark to the plugs when they're out of the engine but not strong enough to jump the gap when they are in the engine.
Could be worth checking the idle control valve/auxiliary air valve, if it's not opening it won't provide fast idle so the engine will flood easily.
There has to be something that your guy has either misinterpreted or just plain missed. If the plugs are getting wet, then fuel is reaching the engine. That means either you have no spark in the cylinder or the fuel is poor quality - Easy-Start or similar may provide the answer to this.
