The only thing about digital is that it is on the memory card and/or the computer and you have to find it later. So the key is to be as organized about the photos as you are about the parts, and set up folders for each bag or set of bags and sort the pics into the folders daily.
But I can get my cell phone or old 790 into a lot tighter places than the Polaroid ever could.
(your hood seal pictures come to mind)
close focus is a lot better and you can't zoom an exposed Polaroid image.
If it were a long term project I would probably dedicate an old device or keep a separate microSD for just that.
I know your iDevices don't have removable memory or micro usb ports, but images could be transferred to their own flashdrive or something, couldn't they?
Don't get me wrong, digital is by far the best way to go. It just takes some discipline. I use an old, OLD Nikon 990, which was their 2nd in a series of twist cameras where the lens section twists from the display section. That let's me get places I never could have otherwise, like the hood seal shots. And, that camera has a macro function that is excellent. So, while I have two Nikon DSLR's so could dedicate one to the shop, the old 990 is better by far. You don't need large or high megapixel pictures, just something around 500kb.
As for dedicating a card, you could do that. I have since I have several cards, but I also transfer them to the shop computer and then sort them into folders. That way I can get back to them. However, I also upload many of them to albums on FTE like Engine Teardown; Suspension; Power Steering; etc.
And the iPhone gets used for some things, but rarely as it doesn't have the focus nor flash controls I want. But, in a pinch I use it.
T18 to ZF5 is pretty straightforward, relocate the crossmember, swap out the hydraulic line, and modify the tunnel cover for the taller shift tower or swap for one from a ZF5 truck. I think the driveshaft also has to be shortened about 2".
I had wanted to convert from C6 to ZF5, but the engine started making serious noise, so I went for a complete engine/trans swap that is a bit different.