Smaller Exhaust?

I have a 74 duster, /6 about to be a 440. I am planing on buying a schumacher engine swap kit (headers, k-member mounts, torque strap) and Im going to run purple hornies... this is a street car... so my question is I want a loud exhaust, and the old style glasspack crackle. so I was thinking about running small exhaust pipes to get the good back pressure and loud pops, how small could I go? i figure as long as you have a nicely tuned carb it should be ok to have a lot of backpressure. ( so you still get the good sound ) any ideas? suggestions? comments?

thanks a lot!