a C-body is really fitting to have a big block. I would think a 383 would be more appropriate for the car and boost the fun factor.
A newer OD would most likely restrict you to a small block but there are options.
either an LA or a big block would open up your options and make parts a lot easier to score.
I am a former C-body owner (I had a 70 sport fury ) so I know they can be fun cars but the crowd that is typically into them is not as diverse as the A and B body crowd. The Abody crowd has been the most fun for me because there is a very wide range of styles and creative people here.