Re: 305 hop ups
Honestly, sell it and get at least a 350. Its hard to hop up those really small motors. They've got small cylinder heads, and small displacements, and its tough to make power with them. I played that game with a 283 I have. Ended up building a 383 out of some various cores I had around. Should have done that in the first place.
I'd definitely save your cash on the intake. The performer is just an aluminum version of the one you already have - its lighter but won't flow any better. A better cam might help some. Headers, small tube, 1-1/2" primaries, might give you a boost. But are they worth it? If you do decide to go with a bigger motor later on, neither the cam nor the headers will be any good for your new motor. Sure you could go oversize now, but you'll also have crappy performance now too.
Save your $$$. Or spend it on other drivetrain mods, new paint, a winch or something you can use on a new engine. You will be dissappointed if you spend it on your 305, and out the cash.