Use a copper line bigger than what you need coming from the compressor...it dissipates heat and could go several feet. Most don't use very much air volume, but slowing the hot air down from a large diameter will help to cool it.
Those are nice looking tires on the rear. I would keep them for now and would consider doing 10.00 all the way around. But I don't like budd rims, so would be looking for a no-offset rim (front) if I wanted 10.00.
What I would replace is the fronts. I'd go to a lot more flotation. The 11.00 is very close to the OD of the 14.5 on the A3 and you will find several members that use the combination, 14.5 on front on A3 wheels and 11.00 on the rear budds. if you go that way, there is a modification to the spring perch that you should research for front stability.
For a while, use the 10.00 on the rear and get the front dialed in with the 14.5....then find a set of 11.00 when you have other things working/replaced/rebuilt for the rear. Stay off hard pavement when the front is engaged and you should not have much problem.
Looks like a worthy project....a good deal. The hard top is a good advantage and of course the winch. I think threaded hole in bellhousing is for water fording....put a plug in it for deep water (and remove later).
If you are going to do your wheel bearings, why not put new rubber in the wheel cylinders and new brake shoes?