Lots of good stuff here in the FAQ section of Nitrous Direct's pages.
There are also instruction pages to look over. This information is general and although all the companies seem to have different jettings for their stuff, the basic concept is pretty much the same for the plate systems, and this'll give ya a fairly good idea of the do's and don'ts etc...
Basically a stock motor will handle 100-150 pretty easily. Mods would be required after that. Since you're building your motor with nitrous in mind, you could gap the rings a bit more (contact the manufacturer for specs) and I'd use forged pistons. That would put you in good shape for up to 200 hp.
If you intend to run 150 or more you'd need some kind of nitrous controls. A means of controlling the ignition timing in particular. You'd probably be looking at running fuels of 100 octane or better if you intend to run in excess of 150 hp too.
FAQ (http://www.nitrousdirect.com/faq.html)
Nitrous Direct pages (http://www.nitrousdirect.com/)
Here's the Holley (Nos) FAQ page. Basically a rehash of the previous.
Nos FAQ (http://www.holley.com/TechService/FAQ.asp?category=NOS)
Oh yeah, wsuwrhr makes a very nice bottle mount...........sheeesh what was I thinking?