Don't go any bigger than 600 cfm, there's no reason you'd ever need more than that with a street 318. I'm kind of in the same boat, I'm building a street 318, but a little different than what you have in mind. First off I'm going with a pair of cleaned-up (and maybe ported) #302 318 heads, along with a used Edelbrock Performer intake off eBay (once I find one), a Lunati Voodoo 256/262 cam, stock exhaust manifolds (for cost and simplicity), and a Carter ThermoQuad carb (Mopar equivalent to the Quadrajet, used on many vehicles in the '70's and 80's with V8's). For ignition I already have in the car a Mallory HyFire 6A box and Mallory canister-type coil, with a stock replacement electronic distributor and all-new plugs (NGK V-power) and wires (MSD universal V8 8mm).