What rear gears do you have? What's your final goal for the car as a whole?
It's fine to want a cam that sounds good but if you're going to spend the money doing the upgrade, you might as well plan for the future. It's worth noting that what sounds mild in a 340 or 360 will sound rougher in a 318. I really wouldn't go any bigger than an XE268h on a mild 318, and even that is pushing it. With the right supporting mods, the cam will perform decently and sound awesome. Swapping springs is easy and can be done with the heads on. You'll also want to check pushrod length and lifter preload with the new cam.
I know you mainly want the sound, but if you can get something that performs better AND has the sound you're looking for; it's a win-win. Going fast AND sounding good is a lot more fun than sounding like a top fuel dragster but being slower than a V6 Mustang.
