I've seen A LOT of posts about making HP with a 318-So why is it so ???

I said torque.

It’s a whole different ball game.

If you can carry that stock 340ft/lb all the way to 6500rpm, you’d be making 420hp.

It’s easier to increase the HP than it is the TQ, if you’re not making the motor bigger.

For big HP gains, you try and make more TQ....... and move it up the power band.

340ft/lbs at various rpm = HP
2000- 129
2500- 161
3000- 194
3500- 226
4000- 258
4500- 291
5000- 323
5500- 356
6000- 388

The stock early 318 is rated at 230hp@4400.
In order to have 230hp@4400, that tq peak of 340ft/lbs@2400 has already dropped down to 274.5ft/lbs@4400.

My 318 from 30 years ago is making about 50ft/lbs more at 4400 than the stock 318 makes.
That moving of the tq peak from 2400 up to 4000, and its ability to carry the tq higher is where the extra 60hp comes from, even though the peak tq output was lower(328 vs 340).

Along those same lines........ for NA stuff...... anytime you see that the TQ number is noticeably higher than the HP....... it’s a pretty mild combo, and it’s peaking fairly early.
It means the tq curve drops off fairly quickly.......and it didn’t carry it high enough to have a better impact on the HP number.
Or...... in the case of some of the hotter factory combos, like a Hemi or L88 Chevy........ they’re giving you what the hp was at that rpm...... not what the “peak” hp was, or at what rpm it occurred.