Rebuilt top end of engine now carb idles much higher?Please help

I'm not telling you to degree the cam.
Just making a suggestion as to why the tune has changed
If you are 100% sure your dots were correctly indexed, in most cases that's gonna be close enough for maybe 90% of guys.
What I am saying is if the last guy installed the cam at 8* advanced and yours came in at 0* advance, that is a huge difference.
Does it matter?
To intake manifold vacuum, yes. To cylinder pressure,yes. To absolute power,yes.These are numbers.
To you, a streeter; not much.unless the cylinder pressure tanks. But the alloy heads took care of that. So yur good to go.

Yur on the right track with proving the TDC mark, and with searching for a vacuum leak.

BTW;
I have an Eddy-headed 367 torque-monster. At one time, two decades ago now,lol,, I was running a Mopar 292/292/108 cam @11.3 Scr. That cam idled down to 600 in gear (manual trans), and pulled itself along on flat level hard surfaces, with 3.55s ........ at 5* Timing. Point being, when you get the fueling right, you will be able to idle that bad boy right down, using timing.

Your low-speed fueling consists of
fuel-level
Transfer slots
idle enricheners (mixture screws)
airbleeds
Idle-air bypass; aka the PCV, and secondary leakage around the butterflies..
And in your case, it looks like a 4-corner idle system, so you gotta keep them cooking at the same time.

Idle-timing does not matter. Don't get hung up on a number. You can idle that monster anywhere from 5 to 25 or even 30 degrees, it does not matter. What really matters is to get the transfer-slots and mixture screws playing nice together, and to get the off-idle tip-in to not hesitate or stumble. It starts with your transfer slot exposure, underneath the butterflies set to a lil taller than wide, and the mixture screws set in the middle of their adjustment range; then leaving them there, use timing to set the idle speed to whatever you want or need.
If the fueling still ain't right, you need to add/subtract air thru the idle-air bypasses that are available to you. Or add/subtract fuel from the transfer slots in tiny increments. Always followed by adjusting the timing to control the idle-speed.