Mill decisions

I'm having a hard time deciding on what to do down the road. I can't seem to get any interest in my 340, and I don't want to set this car up for a small block first, to only then have to re-do it for a big block. Thus I'm looking at doing a big inch small block down the road. I realize I'll end up with different headers from one to the other which is fine, as I'm looking into something like a W9 cylinder head or something with some oomph to work with the big inches and nitrous set up. I'm looking for around 11:1-12.5:1 compression and running on E85.
The car will see some street time, so a completely filled block is out of the question, and so is an R3 block due to $$$. I don't want to be sitting at home on a hot day because I can't cruise my car down to the car nights at the local spots. Don't care if it won't last 80K miles so spare me that argument of the block not lasting at this point. Not being a jerk, I'm just not whiping my butt with 20 dollar bills.

Questions are this:

High flowing race heads for the SB Chrysler's are what?

What heads would you run? I'm looking for at LEAST 200CC intake volume.

What inch would you run? 408? 434? Something else?

I'll call the cam and converter companies when the time comes for them, but I'm wanting a rough idea of the basic components. I won't be skimping on the fuel system as I'm playing with nitrous again, and we all know that's where the problem starts when playing with the sauce.

Thanks for the input fellas,

Dustin