I was once 15 myself (ok, a looooong time ago) and I recognize what you’re thinking. Here’s what I finally learned, hopefully it will help you get ahead in this game.
HP = (Torque x RPM) / 5252
The 5252 number is a constant because we’re talking about a 4 cycle engine (power, exhaust, intake and compression strokes).
The Butt Dyno matches the torque curve more than the HP curve. As you can see from the formula the only way to increase HP at any given RPM is to increase the torque at that RPM.
So why not just raise the RPM to raise the HP number? Because as the RPM goes up, so do wear and friction. And those cost you torque! If you’re really unlucky you get to watch what happens when a rod exits the block at an extremely high rate of speed…
Turning a 4.3L engine in a 24 year old Sonoma into a Corvette killer will cost about as much as just buying a good used ‘Vette. There are no demon tweaks, just cold hard engineering realities.
Establish a reasonable redline for the engine of roughly 5500 RPM. For a naturally aspirated 262 cubic inch engine I’ll pick 1.2 HP per cubic inch as the HP goal that will still keep it street driveable without overheating and so on. That’s pushing 315 HP. It also assumes that there are aftermarket parts available to reach this goal - and I wouldn’t bet on it.
If you’re determined to build gobs of torque with a V-6 below 5,500 RPM I think the best options would be turbocharging or nitrous oxide.
Read everything you can find on these subjects. Bentley Publishers put out a good book on the subject written by Corky Bell (IIRC) and is called Maximum Boost.
Buy Maximum Boost: Designing, Testing, And Installing Turbocharger Systems Paperback Book By: Corky Bell from as low as $16.36.
Nitrous kits should be fairly well designed, just don’t try to go too big. You may need some fabrication skills, I don’t know because I’ve never installed one.
And once the engine is building all that power you have to get it to the pavement without a lot of tire hopping and spinning. So read up on weight transfer and how the suspension works. Best to bring your math skills as this involves engineering topics.