I hear the sentiment of getting bored after completing a restoration from other people too. I don't have that problem...I never complete any of mine, only customers at work and I'm usually way beyond ready for them to leave...
I would LOVE to get a few of mine to a level of completion that they are nice drivers.
Don't you have room to keep it and feed your need to work on something with a new project ? A '69-70 Chevelle would be a cool project, but anything fairly clean and solid seems to be rather expensive just to start with.