I'm familiar with Tubbed but what's Chassisied?
Anyway, I've got my El Camino ('82) and I drive an '85 Regal to school. I have not seen too many G-bodys with really custom interiors. Some of the nicer interiors I have seen have a lot of parts borrowed from the Monte Carlo SS and the Buick GNX. I have done some with the interior of my Elky, which currently has '90 Trans Am seats, a Megashifter and some tasteful guage work. My factory Tach stopped working so I hung an Autometer Monster Tach on the right side of the cluster so you can barely see it when you look inside through the front window. I replaced the radio with three 2 1/16" guages. I'll have to get some pictures to show what it looks like. I have yet to build a console and work over some of the nooks and crannies the way I would like too. I've been too busy trying to go fast to worry about the finer points of my interior.
If you come up with some examples I would like to see them.