genosr, I don't know of the companies who make them, but I do believe they are out there. You might want to send Racer X a PM asking for his input. He's the guy that plays with all that stuff.... If you can't find anything through google, I know APE engineering
www.aperaceparts.comhttp:// can make anything you want....
If you find some, please post up so we can add it to our ultra-list of 250 specific parts.
Delta:
http://auto.howstuffworks.com/camshaft.htm
What genocr is going for, just like X did, is be able to change the characteristics of his engine. He probably wants to increase horsepower by replacing his stock cams with exacerbated cams (camshafts), meaning the lobe has a much more square shape, and keeps the valves open longer to get more air in/out.
If you do this, you usually also change out the valves and valve springs to be able to deal with opening/closing faster. Once you read the article, feel free to post questions....