You need a special puller because the pulley is shrunk onto the */C shaft with a very tight interference fit. The pulley is pretty flimsy and a regular jaw style gear puller will just destroy the outer part without removing the hub.
A 3.4" would be right for your situation since you have no other modifications. Most people now are buying the modular style pulley which allows you to change a pulley simply by unbolting the old and installing the new without the hassles of the interference fit. You may be able to rent the puller from who you buy the new pulley from.
The only difference you'll notice is at WOT in terms of drivability.
I got mine from ZZPerformance, they also rent which is the way to go as you only need it once. I went with the modular pulley system which now allows me to swap out the pulley in minutes with no pulley puller.
The 3.4" is good size to start with untill you upgrade your exhuast (headers) and valvetrain.