NO NO NO NO NO NO NO
That car has made it 40 years that way. DO NOT CHANGE A THING. I would love to see that car. If you were at the Knott's show, I probably would have spent more time at your car than any other car there.
Keep that engine bay like show room. Take lots of pictures to keep track where everything is routed. Never turn in anything as a core. You can rebuild your master cylinder for example.
Make sure you don't lose your engine tag, or distributor tag, or carburetor tag. If you haven't taken the rear seat out, the build sheet is in there.
You could upgrade the dash with a tach and gauges, and a rim blow steering wheel. You can have fun hunting down cheap parts for this.
I envy you.
That being said, my 73 Convertible had a 250 which was replaced in 84 with a V8, and will be replaced in 2012 with a bigger V8. So, what do I know.