You appear to have adone a systematic check.Here"s what I would do additionally.
Did you check to make sure you had the requisite FAT, BLUISH-WHITE SPARK, the color of lightning? check the spark right when it dies. A worn distributor bushing can cause poor running after start up so check the lateral play in the distributor shaft.
By all means check the float setting. M-S carbs are very sensitive to this adjustment.
Have you cleaned the carb thoroughly? That"s the secret to a good carb rebuild (ask GBinMT). That"s probably more important then new parts unless the old parts are obviously damaged or worn.