For the future...Small or Big Block?

Hi,

maybe you will think i'm not thinking about the rigth thing yet, but i'm trying to figure out what to look for in this summer swap meet, and exposition...and junkyard.

So since I still have alot to do on the car...but mainly the drivetrain. Rigth now the car has a 318/2bbl, 904, 7-1/4 combo !!! I don't want to keep it that way.
Also since it's green and 4 doors, I want something to surprise the curious...That car will never have the look and value of a 2 doors, so I tought "What the heck...do something to do make it special!!" ... So it's either a good 350-400hp 360cid ... or it's the Big block way (383,400 or 440 don't know yet).

The front end is redone brand new with a late Dart disc brake setup. V8 crossmember.
So what do you guys think...Small or Big Block?
Is it much more expensive to work on a Big block?
Price versus equal performance?
Installation of a big block? Not that bad or it will be the worst experience of my life?

Thanks for the help :-s