I hate to say this Dan, but I think you're really going to struggle with this one!
The 'feet' that come with the cage are just about useless, they're 100% generic boxes that won't fit your shell in any way, they need so much trimming it's unreal, mine are the boxes that came with the cage, but they took a LOT of work to fit correctly, and they didn't come with enough metal either, I had to get some more sheet to close in all the sides.
Also, your carpet will have to be removed for the fitting, so if you want to keep it you'll need to remove it, then trim it and refit it after the cage is done, fitting the cage requires removal of all the tar sound deadening around the feet plates, and the metal to be cleaned up so you can weld, so be prepared to take the carpet out to install it, even if you're putting it back in afterwards.
As for the head lining, you're going to have some serious issues there, my cage is 2-3mm from the shell on the top corners of the main hoop, hard to see in the pics but it's properly tight:
As for the front legs, they're jammed up solid against the shell, and needed a jack to get them into place, I also had to cut the tops off my A-pillar trims as there wasn't a hope in hell of them ever going back on, because the clips were cut off, I drilled and tapped an m5 thread into the pillar, and held my trim on with allen key bolts
Can just about see the bolts if you enlarge this pic, and possibly the next bit, which you might not like:
Now, brace yourself for this bit, as I think you're REALLY not going to like this:
You've got to cut your glovebox lid up!
Sorry for all the bad news dude! hope it's not too much of a downer for you.
The thing to remember is, roll cages are for race cars, so they make no attempt to fit in around the standard luxury things like trim in a road car. You'd need a show cage for that.
It'll all be worth it at the end though, just think how awesome it's going to be!