High gear and a big hill is what I tend to use rather than the brakes in isolation, relatively easy to get the car to sit at 1000rpm and 20% throttle like that.

Set of rollers makes it childs play of course, if they are like DD ones where you can force it to hold a load site!

With regards to idle AFR, I tend to aim for mid 14s but often find cars sit happier in the 12s or 13s or whatever, if thats the case then I just let them do so, its such a TINY amount of air, that wether its one 12th or one 14th of its mass that you add a fuel is pretty much irrelevant anyway as its such a ludicrously small amount in the first place.

I used to obsess about trying to get idle in the high 14s as thats what textbooks imply it should be, but these days I let the engine tell me what it wants not a text book, epecially when dealing with cars with no ICV that mean you have slightly larger than ideal amounts of airflow on a warm engine at idle in order to allow you to have enough airflow for when its cold, so you end up with retarded timing and a rich mixture to hold a steady idle as you have no way of limiting the airflow and if you run at leaner mixtures the revs want to increase unless you take even more timing out, and thats worse than just running slightly rich IMHO.

So is a matter of compromise between what theory suggests and what practice dictates.