use some flammable carb cleaner, Berryman's B12, or propane around the intake manifold first to look for vacuum leaks.
disconnect the fuel hose from the carb and see how fast fuel flows into a metal or glass container.
If you get a good flow then the only thing left is the carb in which case since rebuilding it failed, here is a new OEM one
https://www.amazon.com/dp/B001768ULM?lv=shuf&channelId=500&plpRedirect=mhFallback