Question about aftermarket crystals and sources(AR coatings, etc...) for 212/Pam chronos

[Ephry73]

I have a very nice 212j case that I sourced before the summer and recently received a nice dial from W0lf that I plan on using on a 212 type build. I want to have a nice daily watch that I can throw anywhere, but also has a full working chrono. I do have a bi-compax just waiting for service. My question(s) has to do with sourcing a crystal and possibly a colorless AR inside coat. Where to get? Also, are there any solid case backs that fit the 7750 chrono 44mm luminor cases? I want to minimize the water leaking points on the watch. So far I have the watch as a "sketch in my head" once I finish a few recent projects and other "things" I can tackle this.

44mm 212j case

24mm Accordion diver strap

7740 Bi-Compax movement

212j Hands to relume in SL and match the dial

212j 1950 LFP dial

Of all of the modern Pams out there this one really sings to me.