350 hp out of a fairly stock 340

I actually like Nick and his channel. Yeah it's drawn out but they're openly trying to make a show of it.
Nick himself seems likable enough and fairly trustworthy. My issue with the video length has to do with easily-skipped or time-lapsed stuff. He should take editing notes while watching This Old Tony. I don't want or need to watch a cam breaking in. It's not a how-to on swapping a carb or adjusting timing, yet we're dragged through multiple instances of the same procedures in real time. Simply put:



(Just for you, @lemondana , @pauly , and @Ironracer )

They show the real stuff that guys deal with when tuning. And they also illustrate that bumping the timing and changing jets, while that works and is important, is not going to turn a turd into a fire breather.
One thing I did like about this video was his unintentional dispelling of a long-held belief: "The best igntion timing is just shy of spark knock." The only time that's true is in a knock-limited engine. He took this particular 340 to 38° without detonation, but also saw no gain and moved it back to 36°. Smart move. Real-world, I'd probably back it down further to 34° just to have a margin for error (exceptionally hot weather, bad tank of fuel, etc.). I don't know about you, but my street cars don't get run on fuel straight out of the VP110 drum.

I tend to think the numbers from his Dyno are real, not inflated.
That's really a matter of the correction factor he uses. That's how we get "happy" dynos, like those used in every car magazine article ever published since the dawn of computers. Nobody publishes the factors they used, but if you "correct" an engine to 40°F and 250' below sea level, you can generate some startling numbers from mild combinations. Startling numbers sell parts, and selling parts (advertiser dollars) is the only reason magazines exist.
Suffice to say, nobody publishes the dyno numbers using the room conditions in which the engine was tested. Some extent of correction is understandable since dyno cells can get hot, but publish the factors used. Can we duplicate them in-car where we live? Probably not.