I have a Wilson ambi on my Kimber. I'm having an Ed Brown installed on my Nowlin. I don't know enough to install them, though. Luckily, I know some really good 'smiths. My Kimber's safetey has no play. My number one criteria is making sure the safety is thin enough that I have to problems accidently wiping the safety off as I reholster. I find these two sufficiently thin, if you get the "tactical" models.
When using a "normal" 1911a1, I just move my thumb over and push it down on the draw, and back over to shoot, and move the thumb back over the slide to push the safety up to reholster.
I don't think there is any other way to do it.
This is the law:
There is no possible victory in defense,
The sword is more important than the shield,
And skill is more important than either,
The final weapon is the brain.
All else is supplemental.
- John Steinbeck