Okay one80, let's talk about this. I started out exactly where you are... I loved the look of a Big Crown, and had to have one. "Only the best will do!" So I started researching.
This is most important. Research. Know exactly what you want. Then research more... who makes the parts to build what you want?
Armed with that knowledge, start acquiring parts. I recommend you find the dial first. You'll find there are complete crap Big Crowns out there, then there's a middle ground of pretty nice pieces that look perfectly good to 95% of people that see them. Then there's a 3rd level that are nearly perfect. The dial sizes are not the same. So the size of the dial you find determines what "level" you're going to build.
I wanted perfection, but there were no dials like that after 2 years of looking. Next was the middle ground with Silix sized cases and dials to fit. There were a lot to choose from and I picked the best I could find. That dial determined everything else and I built a really nice Silix sized 6538 with a well aged dial and hands, and Athaya 8mm crown. It came out really nice. It wasn't the end result I really wanted, so I wore it and kept my ears open for the "right" dial.
3 years later the "right" dial fell from heaven and I grabbed it. It was smaller so that meant everything had to be procured again. I got a great deal on an MQ case (or so I thought) then had to find a bezel, insert, crown, tube, crystal and hands. I went gen for everything except the case and movement. That meant selling the Silix to fund parts, then I started building. I chose an ETA movement for parts availability, that caused tons of other problems like stem misalignment, case fitment, frankenstein stems, and expen$ive hands that wouldn't fit the movement. So I sent it to 4 builders to see if they could fit the hands to the watch. Finally Phong got it to work.
Now I've got the final piece I wanted, and it's everything I hoped for. It's magnificent. I get massive enjoyment from it, but it took over 6 years to accomplish. If I'd been in a hurry I'd hate it now. Instead I treated it as a long-term project and built a mid-level piece along the way to take the edge off. That helped a lot.
Here's the Silix piece
Here's the final piece ... not that different