How long does it take to change a c orofice tube

I would suspect a gasket failure...

The control switch is vacuum operated. There is likely a break in the tube that starts in the engine compartment.

possibly low on freon or clogged orofice tube or bad fan on radiator. too many variables

yes you can still change oil with oil drained remove dip tube extract dip stick replace tube Then repair/replace dip stick, fill as per normal

the valve cover gasket and tube seals should come in a set. if they do not they still have to both be changed as the cover has to be removed to change the tube seals.

Double check to make sure you didn't cross any of the spark plug wires, also, you should ppen the carb and drain out any old gas/moisture that may have accumulated in the bowl. I recommend buying a carb rebuild kit and a spray can of carb spray cleaner and cleaning all jets, orofices etc and the bowl and getting fresh fuel in the carb.
You can also run some crankcase cleaner in to your oil. If it's set for a long time, your oil can get sludgy and you may want to run a crankcase cleaning product in the oil and then get the oil changed.. That will get all the hydraulic lifters opened up and pumping and might solve some of your issue.

orofice tube could be plugged

I changed the tubes.

It is possible the tubes are leaking at the bottom but highly unlikely. There is next to 0 oil pressure in that area so the tubes would actually drain if leaking. I would start with the tube seals and gaskets as you have already planned and check it again later down the road like at the next oil change interval. You're on the right track for the repair, just be patient with the intake plenum and you'll do fine.

yes take the 10mm bolt from the tube and wiggle the tube up out of the way