I'm using the 6L80 in my '76 restomod. I've had both transmissions, the 4L60 and the 6L80 as daily drivers. I favor the 6L80 over the 4L60 because of the gear spread. I just like the more subtle shifts, up and down of the 6L80. In the end their over drive ration are similar. Some say the 4L60 can be built to be a little more robust. I'm not sure because racing or performance driving is not high on my list for this build.
The engine is going to the machine shop soon. While the machine work is being done I plan to tear down the 6L80. So' I'll be posting a lot of photos of the teardown soon. And sometime after that I'll be posting photos of the block and transmission sitting in the bare frame.
But for now, a photo added of the 6L80 next to the nearly bare 496 block