So you want to brag about having a small cubic inch motor like the 327??? Shoot, if that is the case, go 283 or smaller for that 'exotic' apeal, but you'll be slower and wondering how the L6 guy just ran you.
I'm not trying to beat you up, but you need to David Vizard's book on building the small block Chevy on a budget. He has some great info on why you go as big as possible. Your 400 ci engine idea is right on track though but they are getting more difficult to find from my own experience. I'd love a good 400 block to start with too.
Since I had trouble finding one, I went 350, which is a venerable motor, and can easily be made into a 383 like Mikelly mentioned. It all costs money, but you have to decide how fast you want to go.
Davy