We used the imperial services kit on my dad's 65 coronet with a 66 trans (the 66 has the same spline pattern, so he used the same converter that was with the 65 trans).
We are using a manual valve body in the 66 trans.
It works OK, we have tried adjusting every which way and can't get it perfect. As it is now, the 2-3 shift requires pushing the shifter a bit further towards neurtral than should be. But it's not a race car, so it's livable..
I'd give the A&A one a try if I had to do it again.. maybe the geometry or something is better than the imperial services one. Or it could be the exact same. I didn't even think imperial services was in business anymore..