Engine sputters, stalls while driving. Fails to immediately restart.

My B2200 drives well for the most part but will inconsistently sputter and struggle before stalling while driving as fast as 50km/h. It's possible to maintain it via dropping the clutch, but only helps make it a little further before pulling over. The engine will also fail to turn over immediately afterwards, usually requiring a 15 min break before it'll go again. When first starting the engine it also has the tendency to blow white smoke through the exhaust at high revs.

Since it first occurring i have:

Replaced Fuel filter
Replaced the ignition coil.
Cleaned my vacuum advance to distributor
Sprayed and used carb cleaner.
Ran seafoam cleaner through fuel and carb. (what i have been dismissing the smoke as)
Oil change
Brakes. (likely irrelevant)

I am at my wits end; if there is any more information i can provide.