what would be your diagnosis?????

Ok, so, the intake is off we have to wait. I get that. I also get that you have been fairly systematic and thorough.This points to you either having a lot of help, or that you are fairly knowledgeable to start with.And you have tools.So my guess is you have been down this road a time or two already. And I know it can be frustrating to keep hearing the same thing post after post.
But here it comes again; since the carb is off, get after the T-port sync. It is so easy to do, you'll wonder why such a little thing could be such a big deal. If you need help with this, it's easy to explain, and every cam bigger than about 210@050 needs this addressed to some degree or another. Your cam is not that big, so a minor change can make a big improvement.

Ok, it's Sunday. Sunday is family day,but the kids were home last week, so, I got all day, and so, I'll just jump in here.

-Put the throttle control on the curb-idle stop, and keep it there making sure the choke mechanism cannot interfere. Flip it over,upside down. Get eyes on the transfer ports. They should appear as little square openings, to, in your case, perhaps a teensy bit taller than wide. Use the curb idle screw to make it so. Now, counting the turns, back out that same screw until the screw just comes off the stop, indicating that the primaries are fully closed. Eyeball them and prove it! Write that number down.
-Next, move to the secondary side. With the primaries still fully closed check to see that the secondaries are also fully closed, that the linkage is not holding it open. Then find the secondary cracking screw. Screw it out until the secondary throttle blades just barely stick to the borewalls.Then open them 3/4 turn.
-Now, flip it back right-side up, and turn the idle-speed screw back in the same number of turns that you previously backed it out (you did right it down, right?).
-Finally readjust the mixture screws to the base setting, which for Holley-types is 3/4 turn out, and for most others is 1.5 turns out.Now this is the really,really,really,important part. This is your baseline. If you get lost after this,return to the baseline.This is why you write stuff down;so you won't have to pull the carb off again.

And finally the quadruple-really important part; from here on you will not be touching the idle speed screw again.Unless I, or somebody smarter than me,(and there are lots of those guys) says so. You will be setting the idle speed with idle-air bypass (PCV leakage or secondary cracking screw), or idle timing;NOT with the idle speed screw.

When you get it back together,your target idlespeed will be 700 rpm.Your target idle timing will be 16* to 18*, +/- 2*. For a streeter I like the lower numbers, cuz I have an easier time tuning the Vacuum advance later. And a streeter quadruple-really needs the V-can working.
-If you cannot achieve the 700 in Neutral/Park, with the outlined method, something else is wrong. Either she is sucking air/fuel somewhere or the timing is out too lunch.
-Your mixture screws should now be working.If not, that's the very first thing I wanna know. Nothing moves forward until the mixture screws work and work best at between 1T and 2T.

To be continued; after you are up and running.