91 1500, 5.7, 700r4/4L60, 3:42 gears, 4X4.

When I was younger I had several Chevys (64 Impala SS, 69 Camaro RS) with 327s and the dreaded powerglide tranny. I was able to put what I guess is actually new valve bodies that made the shifts a lot more solid but more important dramatically improved the power at the wheels. I guess my question is, are the newer transmissions already set as high as they can be for power and performance or does a shift kit do the same thing? I may be mixing up two different things or are the shift kits the same as a valve body?