Valve / Piston Clearance in 383

along with rumblefish's reccomendations, i'd add

carb jetted/tuned for combo ... if it's very used it may need a rebuild, if it's out of the box it probably could use some mods to match the engine.
put car on a diet (lose some weight) - lighter wheels, remove everything from the car you can for race (spare tire, etc)
also what air cleaner are you running?

Carb was rebuilt long ago. It's an older style 4779. I'm running K&N open top air cleaner.