383 Wont Idle with new to me 800cfm DP. Idles and runs ok with Edelbrock/AFB

I got to laugh "Holly people" LOL I think either carb works well if it's in good condition. I personally like Edelbrock's cuz they seem less finicky.
now I thought I was pretty damn good at those 1406 s and have a couple myself. I've taken them down to nothing and put them back together with kits and have had great results. But this last 1406 that I had same problem, ran fine but wouldn't idle said the last person that I owned it. I went out but a brand new rebuild kit and dipped in a vat of carburetor cleaner. Then cleaned every orifice out with spray carburetor cleaner. Then assembled it and it was shining like a brand new penny. Put it on my car and it ran fine like before but could not hold an idle. I sold it at the last swap meet for $60 with the receipt for the $50 rebuild kit and put it out of my life...
Well the good thing on this 800 is I am not totally committed to it. The guy I got from basically told me to try it out and see if I like it. I was in the market for a carb and price is right. He said it came off his jet boat and was removed for EFI. Obviously I won’t be drilling anything unless I am sure I will use it. I did read about adjusting the secondary stop screw to creat an air bleed so I can lower my primaries into the idle circuit.