Somewhat true - the majority of the fuel gets in at the base, but some comes through the dump tubes normally. Have a look at any carb while running! At sub idle speeds, like 300 RPM, there's not enough airflow to pull it from the dump tubes, so it's like you said.
Remember the float level is just a teeny bit below the tubes, so it doesn't take much venturi airflow to get the toilet effect working.
Did you get that choke blade wired open? If not, no matter what else you do, it's going to be too rich.
But then, How do you know it's rich?
2 different type carbs in a row doing the same thing?
Wondering - if your old carb had been flooding over and put lots of fuel in the crankcase, the PCV Valve may be pulling the fumes from the oil. That could be the source of the extra fuel.
Try pulling out the PCV Valve - leave it connected to the hose so it sucks fresh air instead of crankcase air. It should not make an appreciable difference in the way it idles. Don't just plug or pinch it off - the carb is counting on clean fairly fresh air coming in through the valve.
And - make sure there's a vent where clean fresh air can get into the crankcase, fresh air needs to circulate through the crankcase to keep it clean.
If you see a big improvement, simply change the oil and filter.
Compression - not likely it's affecting it - but - have a close look for what's called blowback.
Hold your hand or a piece of white paper - like notebook paper - over the carb top, about an inch above it - not restricting it - and rev it several times. And/or in a darkened area shine a strong narrow beamed flashlight across the top of the carb while reving it.
What you are looking for is tiny droplets or a mist above the carb. That indicates a leaking intake valve, or an exhaust valve not opening enough - like a worn cam lobe, bad lifter or rocker etc.
Usually a compression test will miss it since the compression test is at cranking speed!
It may or may not be severe enough to cause a rough running engine, but sure plays hell with how the carb works - it drives it nuts! The air is actually blowing UPWARDS in pulses (blowback.)
And of course you have disconnected the lines to and from the charcoal cannister? Sometimes the cannister gets full and causes problems. You said you replaced the hoses. The new hose may be sucking fuel out of it where the old one was leaking and wasn't purging the cannister.
Let us know.