To me a DD is just that a DD. To me it needs to be something I enjoy driving that I need to only basic maintenance too. But my DD is a 2011 F450. My wife has been an MB fan for along time and has had a few. The LX platform cars are still basically the MB chassis that they started with, basically and E class Benz platform. Those are very reliable very good cars. We always seem to have some sort of modern muscle "fun car" for the wife as well. It has been a string of Mustangs until recently where her german car thing came back. Now the current fun car is a 911 Carrera S. I can tell you it is enjoyable to have a modern performance oriented car around. Just get in it and drive and enjoy. I have sold most all of my old stuff in favor of the more modern cars.

If it were me I would sell the Belvedere and buy the SRT8 and never look back. There are plenty more old B bodies out there and new projects are always fun. But Id be willing to bet you will be very happy with the new car to drive on a more daily basis vs the occasion use of the old B bosy. Not like you don't have other cars to go out and have fun cruising around and tinkering with when the urge hits.