The Stovebolt Site Forums The Shop Area Engine Shop 1965 283 with manual choke, need help starting please

Try to get the terms right. You can't get flow from an "inlet". Inlet is a place where something goes in. You were observing an outlet flow. I would not dwell on this if you weren't an engineer.
Now, you are saying you now have good flow. Why? did it suddenly start pumping good and quickly? Don't hold back info even if you did something wrong. We need to know unless it's a miracle. Remember, you started this whole post by saying and confirming NO FLOW, 30 second wait, etc. Figuring out why it is now a good and quick flow is the rewarding part of working on trucks. It supplies info for all of us and helps in the continued effort.
Did you or did you not, replace or exclude filter between pump and carb? Did you or did you not replace filter inside carb inlet? If so, then it sounds like the fuel level in bowl is not adequate or other carburetor issues. BE SURE to indicate info about the carb filter. This is at least the 4th time I have mentioned this. IF FILTERS ARE NEW, then it's time to rebuild carb. Rebuilding is a thorough cleaning out of all passages and parts. Then replacing parishible components and gaskets and setting a few parameters according to the instructions in the kit. All done in a clean big pan. Take pictures before of all sides of carb to be able to reinstall linkages correctly and pictures as you gently take apart.
I will say you are a difficult poster to help. You don't respond to questions or advice, you don't provide specifics, you don't read the info given carefully.
The stalling, heavy use of choke and pumping is indicative of fuel supply, as we have already informed you. Now that you supposedly have good supply out of pump, then it says the supply from carb to combustion chamber is the next issue. There are several things that could be causing it. The best approach is rebuild. I suppose there could be vacuum problems but I go with what you always say: not likely that something opened up just sitting. Very likely carb. Rebuild, get rebuilt, buy new. I don't rust many to build my carbs. Many are just practicing on my stuff. If they are older than 60, I may trust them. I would trust carbking, mike's carburetors and a few others.