Lets start with the simplest, replacement brake hoses. I plan to get some braided ones, but I'm not certain if mine has been lifted. I suspect it may be a couple of inches higher than standard. looking at these, is there any reason not to get the extended ones just in case given that the normal ones are basically the same price?

Next up gearbox seals. There's a leak somewhere, and while it's all going to be apart (chassis replacement) may as well refresh them all I figure. Are there just three I need?
Rear crankshaft, transfer box output, front camshaft

And now the main event lol. My rusty wheel arches need some attention, and my mechanic said it would be great if I could get replacements to make their job a lot faster/easier. I can't seem to find what I need at all. I've found the D1 repair ones, but I guess they won't fit. And I can find wing repairs, but if I'm interpreting correctly these attach onto the wheel arch? Everything else I find seems to be the plastic liners rather than the arches themselves. Can anyone give me some pointers what I'm going to need?

I think yrm are doing D2 body panels now.
Extended hoses are fine either way. Having new hoses is a good practice every few yrs.

Check the intermediate shaft ends for leaks on the transfer box. The O rings can and do get hard and fail.