I would suggest going with their 12 bolt housing/complete rearend over an 8.5. The extra money spent would be well worth it in the long run, especially if you ever decide to sell it or want to put more power to it. Gears and other stuff are in most cases cheaper for the 12 bolt anyway and readily available.
Once you go thru the expense of shortening your housing, putting different ends on it for C-clip eliminators etc etc, a few bucks more gets you a brand new 12 bolt housing with thats not 40 years old. 10 bolt stuff is hard to find and sell, 12 bolt isn't.
I forgot about Moser's economy brake system, probably similar to what Inline, Right stuff, Summit sells.
My Dana (as well as the 12 bolt I had built for the wifes car) has the big Ford (torino) ends. Thats the most common one used and is popular with all the aftermarket brake kits.
You can't go wrong over building your rearend. Spend the extra cash once so you hopefully won't have to do it again. At some point, you'll want to pick up the power level and why not already have that part of the car done, squared away, and ready for the extra power you throw at it.
