I have a 496s with AFR 305 heads DUI distributors and 850 Quick Fuel carbs sometimes when going into gear the motors will stall,I checked the 4 corner idle screws and they where 1 1/4 turns out, it seems like they should be turned out more ,but I could be wrong. I forgot they idle at 950 and the base timing is set at 12 degrees at idle.

Screw turn count means nothing. It's just a ball park to get started. The engine will let you know what it requires.

Get the engine up to operating temperature.

Install a vacuum gauge on the constant vacuum port. Not the one that applies vacuum after the throttle plates open up.

Adjust all 4 screws to achieve the highest RPM and vacuum possible. You might need to back off the idle speed adjustment screw to get back to normal in gear RPM.

It's really quite easy to do. I ended up with my QFT M850 at around 5/8 turn out.

Once in the water and in gear, I did turn them out about 1/8 turn more to richen the mix as there was now a load placed on the engine as opposed to no load while in neutral.

So. in all I am around 3/4 turn out on all 4 screws and have a little over 16" of vacuum on the gauge. The engine starts right up. No black soot on the transom, and no stalling going into gear.

Hope this helps

Adjust carb idle screws as posted above.
if that does not help, You could try more base timing. I’d bump it up to 16-20* and then have the curve adjusted on DUI ‘ to reduce total timing.