Carb or ignition ?
Experimented with initial timing and curves.
BTW
In my 367, the Hughes cam (223/230/110) would idle down to 500rpm ,in gear (manual trans), and pull itself on a flat, level, hard surface. Not a lot of extra power to climb mind you.
It did this with a proper T-slot sync, nearly 11/1 Scr, alloy heads, and just 5* of Idle Advance, and a stinking 750DP on the AirGap.
What I mean to say is this
just because one guy idles his 3000 stall hotrod on 25*, doesn't mean YOU should. Let the engine tell you what the LEAST amount of Idle-timing it will put up with, because we already know it wants , or is willing to PUT UP with high 20s . But like a contrary wife, you can't always give her what she wants.
BTW-2
If you have a 4-corner idle carb, the 221cam in your 360 does neither need nor want it, so I would figure out how to shut it off.
Do I need to drill the primary plate ?
I didn't "need to" , idling at 750/Neutral/14* initial.
But down at 550 in-gear it preferred to have a little, I'll guess because the PCV might have quit being the principal Idle-Air bypass .
So I compromised, and gave her a lil Idle-Air bypass, and reset the neutral idle speed to 700
The thing of it is, My Hughes cam had an advertised of
270/276/110,@.008 tappet rise, so that's not very big, very little bigger than the 340cam, so it idled VERY tame.
How does that compare to your 221/229/112 roller? I'm betting yours is more like 276/284/112, possibly at .006tappet, so that should be lumpy at 650 in gear. The 112LSA will play havoc with your AFR down there, so IMO, forget about the AFR at idle, as already mentioned.