The Rest of the Story...
So I properly trimmed up the interiors according to the seam lines using just sewing scissors. I placed them inside my SgtFang bucket (which is suppose to be 1:1). I stripped out my fans and other goodies so this is a nice naked bucket. The front cheeks fit on nicely with a little give to allow alignment. Luckily, the padded parts are a nerf-like rubbery material which allows it flex to conform to the shape of your helmet.
The same goes for the back panel. I have noticed that you must be careful with storing this as your working on it. I folded it in half loosely back in the box as I was working on it. It developed a small tear of separation where one of the raised detail boxes meets the main panel body. It only did this, though, because I folded it inside out. Once I placed it in the helmet, you could not see the tear any more. The back panel is made of the nerf-like material too, so it is nice and soft. The fitting of this panel was a tad bit wide for the SgtFang and was not forming to the shape of the bucket due to the keyslots. Had the slots been more flush (which you could only do by removing the slot panel all together and replacing it), then the edges of the panel would not extend over the tips of the T-Visor.com visor. It is a very minor issue though and could likely be fixed with minor trimming. I chose not to mod these interior so you can get the full out of the box experience.
The dome fits perfectly into the SgtFang with only a small amout of overlap on the back panel, which is a good thing in providing total coverage. The only shame in this is two of the outlying greebes on the dome are hidden slightly. The front pad does not fit as smoothly, but this was mostly due to me not permanently mounting this interior.
To do a temporary mounting, I tried to use Gorilla Tape to just let me see how it worked. That tape which works on basically anything would not even hold it's own weight. This is due to the releasing grease on the interiors. I HIGHLY suggest those of you who purchase this wash it good. I used warm water and dish soap. Once it air dried, I had not problems with the interiors. Just make sure you let it air dry (do not rush it with heat), since the material is spongy.
I then did a test fit and that is where my experience with this interior leaves me personally very sad. I had the dome & back panel on only and tried to put the helmet on. I could only get it halfway on. The greeb box in the middle covering the keyslots inside area prevented me from wearing this bad boy. I imagine it would be very comfortable, as the dome was thin, but despite my initial worries over lack of padding, it's pretty comfortable. The front padding is likewise very comfortable and giving.
I do not want to discourage people from buying this. I do have a larger head. I wear a 7 5/8 hat size (which is pretty big) and admittedly, my SgtFang is almost too snug. I imagine that it you can comfortably wear a Jango two piece or have room in your 1:1 that you would be good.
I also own a M-DSB Assassin (a custom style helmet maker from Merc land). My version is XL, so it has plenty of room. However, the dome does not line up properly at all due to the helmet's unique shape. The backpanel and front padding do fit, though. So those of you with other helmets not trying for a 1:1 Fett could still use this fine interior.
The last step for me in this process was to try out rub and buff on the panel. It obviously worked extremely well. I did not try painting as weather has not been permitting me to do so. I did test out trimming with primer, Paint and airbrushing with good results. I would highly suggest rub and buff, along with fine airbrushing. You can easily do a fast, simple rub and buff coat, not worrying about the cracks and gaps. this adds to the illusion of depth and works like drybrushing.
In the end, even though I cannot wear this with my Boba (which was the point), I would still use this to turn a spare 1:1 into a full sized "model kit" similar to the mini Riddell helmet. I know not everyone troops, so if you are looking for a fantastic display prop, I would make this your second purchase - right after your 1:1 bucket!