I'm thinking about buying a 84' Silverado with a 305 in it.  Should I be at all worried about anything?  I'm not really ever going to tow anything big or load it down, but I do go off-road and to the beach.  I'm not to up to speed with the 305.  Any info/suggestions would be appreciated.  

There's nothing wrong with the 305. The 305 small block was designed as a torque/economy motor. For everyday driving and light load hauling, the 305 is just fine. Depending on the level of off-roading you're talking about, a swap to a 350 with more torque and horsepower wouldn't be a bad idea.  

If you bought a truck with a perfectly good running 305, you are ahead of a lot of people. If you decide to beef up the power later on, you're best bet it to find a salvage 350 Vortec motor for $300 or $400. These things make sick power for chump change, and can be modded with tons of inexpensive parts. The best thing is that you'll still be able to drive your truck with the 305 while you're building something bigger. Either way, the 305 is cool.  

I bought my dad a 95 silverado and it has the 350 in it. He said it has more power then the 350 that was in his 76 custom deluxe. I wonder what a set of headers and and a K&N filter would do for the gas mileage cause that was his only complaint with it. His is a 2wd extended cab. He claims it only gets around 15 MPG on the highway but for a truck I believe that is about as good as it's gonna get.