So here's a question. When they redrill the holes at 1:50 and 2:05, does it not make the bore bigger and therefore allow more gas to escape the pistons?
Side note, I have to wonder why they didn't restore the truck itself while the engine was out being rebuilt.

At 1:50, they appear to be making the cylinder hole larger. They would then either 1)buy new pistons to fit the larger bore or 2) if they just took off a tiny bit to remove a scratch and it's still within tolerance they could just reuse the old pistons with new rings. In this case, those certainly looked like new pistons, which should be matched to the bore they just cut. Notice at 3:48 you can see ".030" stamped into it, which likely means .030 inches over stock.
At 2:05, I think they are 'dressing' the bore, which puts a cross hatch pattern in the cylinder wall that helps the rings seat and seal.

As to your side note...it's a style choice. Some people love the old, stock, unrefinished body paired with new running gear for a car that looks like junk but runs like a top. At least that's my guess...and that's how both of my cars are built.

It's not unrestored, it's "patina".

Worst mistake I ever made was repainting my '51 Chevy. The patina was on the way to being perfect.
Now I take photos of every worn, vintage car I find so I can faux reproduce it on my '74 Karmann Ghia. There's nothing more beatiful than paint worn through to primer at the edges and the satin luster of old stainless trim.

The patina on my 73 Mustang has progressed to "rusted through" in more than a few places so I'm resto-modding it. It's only a Grande convertible so the VIN doesn't decode rare at all, so I feel ok customizing it.

Assuming this is either the 221 or 239 (cubic inch) motor, it puts out a neck snapping ~65-90hp and ~150-190lbft of torque.

Impressive for the day, and amazing to think it's difficult to find the most basic modern commuter vehicle that doesn't either beat or come close to those numbers.

Yeah, when they drove it out at the end and gassed it I was expect the revs to pick up faster. Sounds nice though.

That's exactly where I am. Some cars you don't own, your just a custodian, preserving it for the future. Other cars...all bets are off.

HA!!!!
The "rusted through" on my 70 Bronco had progressed to "rust held together by spit and paint" in many places...but many more were rusted through all the way around, like my hood which had no edge when I bought it. The windshield frame was only upright thanks to the glass, it peeled off by hand leaving me a windshield with no frame. I've since replaced both, but I still have at least one hole through every panel I haven't replaced. My front fenders are more rust than metal at this point. I have replacements, but I'm waiting for it to disassemble itself. ;-)