I can't say if a Yuki case is better than a Ruby case. My theory is that you just need to buy your parts and then have a watchmaker put your watch together. You're building a replica, so it's important not to obsess.
You can check Phong and Jensen for a set of hands. Or look at what yuki has- http://www.yukiwatch.com/catalog/item/6960394/7159505.htm
When you say reverse panda, I'm assuming you mean a black dial with white/silver subdials- the two that Ruby has look fine to me. MQ is probably more expensive and I've never been keen on buying directly from Vietnam, but I've never heard anything negative about MQ.
I'm thinking that a 721 movement is still a 18K beat movement- I pretty sure the Rolex 722 was also 18K. The 726, 727 and 730 were the late Valjouxs at 21,6K. But finding a 726 is expensive these days.
Here's a 6239 I put together a few years ago- DW case, Vintagewatchmaker.com (Jensen) dial and a V72 out of a Wittnauer