Shouldn't matter if the fuel line and hose is in/routed the same as factory. It's a float or heat soak at the carb.. perhaps.
Heat temp does it run at sitting at idle in heat and cruising down the hwy?
Engine may be heat soaking/temp rise an excessive amount after shut down and maybe an increase in cooling capacity could be the cure... but things like and initial timing increase can help.
Maybe fuel is being pushed , look down the carb after shut down for dripping fuel.
Just start with the easy and go from there