Best bolt ons for a small block

1.) Put a decent curve in the distributor, with initial timing around 10-15*BTDC- see what the engine likes. All in around 3500 seems like the rule of thumb, stock cam may like a little less.
Good wires and brass contacts on the cap and rotor.
2.) Ignition module, like Rumblefish said.
3.) Intake and carb. Eddy Performer and carb flavor of your choice- 600-650 cfm is all you'll need and still leaves room for future mods. Factory 4 bbl. setups work nicely, too.
And one other that some here may not like because it's not "racey" - a stock 360 2bbl. manifold and carb. People give them away. It uses a larger 2 bbl, and 383/400 2bbls bolt right on for an additional cfm boost. All factory linkages and choke, no piecing stuff together. One of the best 'teeners I ever had ran this combo, a buddy even ran it on his dirt tracker years back...
4.) Exhaust is last, since you already have duals- but depending on size and whether it was run off headers or the stock manifolds, there could be some room for improvement...
5?) Possibly rocker arms (and most likely pushrods), if you can find a set of 1.6s for a decent price. It will give your existing cam a bit more lift without having to replace it.
Anything else (cam, etc.) would go beyond your basic bolt on request and necessitate breaking the engine open, which I assume you want to avoid for now.