If you question thereeds or don't know how old they are, wouldn'thurt to check. Good idea would be leak test before you tear it apart, paying particular attention to right side. Flex that boot/manifold looking for cracks/leaks. Make sure slide cap gasket is in good condition.
Wouldn't hurt to remove emulsion tube/needle jet when you clean them, make sur holes on sides are open.
Sight windows on son's carbs can't see through, so I sync by feel.
As to everything exactly the same, if you were more than 1/4 turn different on air screw that might be a problem. One carb body or needle could be worn more/differently. Slide idle screw shouldn't matter as much, unless one slide was 1/8" higher than other.
Have you tried new plugs?