I have the 4L60 from Silver Sport behind my 440 (TrickFlow heads and FAST EFI). Trans works great and package came with everything needed. I looked at all the options and this was the best for me. Regarding the Mopar thing, the good news is that parts don't know the difference, they're just parts. Not one person has looked under my car and came up with their heads shaking. Even if they did, I wouldn't care.
I love the cars that are completely OEM and I love cars that are custom. You just have to ask yourself 1) what is my budget and 2) what is the intended use of the car. For me, I wanted to drive the car hundreds of miles at a time, a good bit on the highway and to not beat the piss out of the drivetrain and to be able to actually enjoy the drive. Additionally, I didn't want to cut up the tunnel, nor have to deal with the NAG1 speed sensor issues, or the GV oil change and added weight.
Different strokes for different folks. For me, it was a no-brainer.
Regards,
John