stock comp. 318, which purple shaft is best?

My advice... if your engine has close to or more than 100k, forget a cam swap. You would just be wasting your time and money. There is a lot more to it than just a cam and lifters. You would probably need new valve springs and of course a timing chain, plus all the gaskets required. Then as soon as you get it all running good, you spin a bearing. Or maybe your rings can't handle the higher cylinder pressure. Who knows? Just wait 'till you have enough saved up to rebuild the whole engine the way you want it.

Now you CAN go ahead with the 4bbl intake, carb and headers. My Dart has a 318 with 140k miles on it. I picked up an Edelbrock SP2P manifold for $40 on eBay and stuck a 500cfm Carter carb I had layin' around on it. Then I put Doug's headers and dual turbo mufflers. It sounds mean, and it will roast the right rear tire. I can just imagime what it would do with a higher stall converter and 3.55 gears and a sure grip in the rear end. No it's not terribly fast, but it does pull pretty good on the low end!

So save your cam money, or put it into gears and a converter. You might also consider an electric water pump and fan setup. That would free up 20-25 horsepower. Or how about just putting 1.6:1 ratio rocker arms. Point is, there are LOTS of things you can do to get more performance out of your 318 WITHOUT tearing into the motor.