There are currently made kits that have similar hardware, they typically run $75-85 bucks. The challenge is finding the stainless outer bezels, that's why I have the later model commercial units, it gives me all the parts.

As for filling the 8" hole, look at the "buckets", they have a flange that fills that space, but again, you need the bezels to complete the deal, and to my knowledge nobody is making those......probably because the market is too small.

Where's the quick you "promised"?