There's a lot of good info in this thread (especially on camaro69's part), but there's one thing I want to address. Nitrous LOVES compression. It's a fair bit different from supercharging/turbocharging an engine. My lt1 has a compression ratio of about 10.4:1 completely stock, and if it didn't have 150000 miles on it I'd feel perfectly fine with throwing a 125 shot at it (with a dyno tune). If you got forged pistons, I'd say you could run a 75 shot without even worrying about getting a tune. If you could come up with another 600-800 bucks for a dyno tune, you could go as high as a 150 horse shot and it'd just eat that 10.3:1 compression of yours up! And you'd end up with enough torque to move the Earth beneath you.

I'm glad you decided on which route to take though, it's the first and sometimes hardest step! lol

 

if your talking to me yea thats my next plan
i have all forged internals and stuff which i could put a 100-150 shot for how hard i drive it usually(which it has about 15000 on the bottom end)

 

I would agree that a nitrous shot of 125 rating wont hurt a 10-1 piston, but I wont go so far as to agree that "nitrous LOVES compression". It may love it, but that doesn't mean you're lower end will love or tolerate that much compression! Forged pistons are a good start, but not the end all to handling truly high compression, and a 10.3-1 ratio with a shot of nitrous, and no special work in the lower end will surely spell doom in time.
My other issue with nitrous is the inconsistencies it can occasionally create, and these occasional blips almost always spell doom for an engine. Should some minor thing happen to restrict or cut off fuel delivery, the lean mixture will be so catastrophic that you may not have anything left to rebuild from. Have the same lean situation with a normally aspirated engine and it will just run out of gas and cough to a stop.

 

Nitrous doesn't increase your compression ratio. It only increases cylinder pressure. More specifically dynamic cylinder pressure. As long as he doesn't hit it in OD at 25 mph any increases in pressure from a good tuned fair-matched shot (dyno tune + no bigger than 150 shot, like I said earlier) will be bled off. Of course if he shoots a 200 shot without any form of tune it'll run lean and he'll probably melt those pretty forged pistons of his, but that's pretty much the furthest thing from what I'm suggesting.

To the OP, in my opinion, if you wanna drop 140 bucks on forged pistons (A great deal, and I think that's how much you said it would be...) then go ahead and throw a 100 shot of nitrous on top of it. Just make sure you get a tune, also.

 

Regardless of what you call it (compression or cylinder pressure) the result is the same; more stress on the crank, bearings, rods and pistons. You can play all the games you want with terminology, but it still requires a very sound bottom end, and hopefully a forged crank and 4 bolt mains.
Chevrolet didn't build a high output small block without using forged pistons and 4 bolt mains. Why would you add 125 hp to any small block and not do at least what the factory saw fit to do on a stock engine?

 

well the 383 im getting has a 4 bolt main, hardened rods, scat crank and forged pistons..but i still dont think i wanna add nos, i mean it would be cool to have that extra boost but once the bottles empty then its back to what you have, n/a engine wise..and i dont really wanna risk anything even if i have forged pistons