You guys should be proud of yourselves. I've been watching, and avoiding commenting because I'm annoyed at the question in the first place, but you all have managed to keep it civil despite being called a bunch of GDFDB's. (sounds like a communicable disease if you say it fast)
This is the one thing that hasn't been said to the OP outright,....despite it being offered in just about every reply.
You are looking for a magic number based on manufacturer claims. If you honestly think that you can take your stock combination, and add this, plus that,...add this and a 75 hp shot of that, and get a realistic uhhh........ guess, then you are sadly mistaken.
A 75 hp shot is never a 75 hp shot of nitrous (it's a manufacturer's educated guess, based on some test mule) Like it's already been pointed out to you,... two identical engines w/ the same mods rarely make the same power. The formula that has also been offered to you for tallying up what hp you have, is best verified either at the track or at the dyno, and your tuner, your brother, hi po part manufactures and yes, even Google are all gonna be inaccurate until you get to one of those two places.
I still don't get the point of your question,....you just googled your HCI combo, and added the ambiguous 75hp gain(all 75 hp gain) to your magic number, and now you are secure in the knowledge that your 302 w/ admittedly worn rings makes what?........425.
If it was so easy to answer your own question, why are you asking it here?
I will venture a guess here, I'm way older than you. Suffice it to say that even if your engine makes what you think it will,...I've had an engine that made 3 times that. All this goes to say that on my current car,....... despite the fact that it has HCI, long tubes, and a manual rack,...when asked how much HP I think the engine makes my answer is always the same...........
I Don't Know, I haven't had it on a Dyno yet.