I have a 360 with 10.9 Scr, aluminum heads. It is a zero deck with the pistons .005 max out of the hole.
I ran this with a 270/280/110 Hughes cam. Lift with 1.6 arms was .538/.549listed. I run the AirGap and TTIs( with H-pipe at the time). I also run an A833 with a same starter gear as you.
No MSD, but similar timing; I ran 14*
So we're practically twins. Well except you are Duster,I am Barracuda.
I am positive your tune is off, or at least way different from mine.
The primary clue is the sluggish mixture screws, with correct T-port sync.
I believe your running float level is too high, making pull-over too easy. The back-up to this is the secondary cracking. If your timing really is in the 16/18 zone, that little cam should not require much if any cracking. Mine didn't. Mine also was fine with a 700 idle.
Here is a test; does it pull 1st gear at idle by itself-no slipping the clutch, on flat level hard ground, Down to 600/550 rpm, before it starts getting jumpy. If it does that ignore the AFR.
This cam has an approximate ICA of 60*. That means the piston is nearing half way up the compression stroke before that intake finally closes
