Hi,
I hope I can anwser some of your questions since I build two 5513 with a Josh case as base.
1. No but the clark is still the best you can get on a budget. You will have to shave the outside diameter down a bit or shave the inside of the retaining ring down for a good fit. The inside diameter is a perfect fit. If you do this right it will also have WR, enough to shower and swim with it.
2. Dremel, sandpaper you name it.
3. I use my dremel to polish the metal parts.
Good luck.