Power is always nice. But I'd also look into getting a suspenion upgrade. If you cant get the power to the ground it's useless!!
What's your budget because the list can go on and on?
Do you have a man. or auto
trans?
If you have a auto you should look into getting a stall converter and a different shift kit.
A tuner is going to be one of your best friends when you do this so I'd look at getting one also.
Getting a 8.8 rear end will help better then the 7.5you have in it now along with gears( but a 7.5 will be fine for now) . Fule pump ect.
When I look for parts I tend to go to summit racing. Yes it's alittle bit more then American mucle. But I've been going to then for a few years now.
You can also look into jegs.com
I'd say make a list of what you want.
Like what kinda of heads not just "stage 3". Post them all on here and you'll get some yea or nea on it if it's a part you should go with.