Very carefully, at an angle from the underside to ensure the top edge of the insert isn't damaged. I did this with my PCG that has a slightly smaller than spec bezel.
Well Bart, you continue to create some fantastic pieces and your dials are second to none! Happy to help where I can. I'm not sure of the diameter of the Yuki insert. To be honest I've no qualms about shaving these slightly, either the outer edge, or the underside for a slightly recessed look. Having said that they fit the Cartel assembly without any problems.
I'm pretty sure you"ll find the llip on your tube will sit flush on the case surface, this is enough to ensure it's straight. No need to install the crown to the tube before fitting. Use a minimal amount of JB Weld, check for any overspill around the lip and inside the tube itself. Use a toothpick to remove it. Clamp the tube in place, let it set overnight, job done.
Part no.: 090ST1242 is the tube for the He Valve not the crown
Part no.: 090ST1232 is the tube for the crown for both cases 168.1653 (PO 42mm 2500) and 168.1623 (SM PRO 300M), plus many other cases too.
You need to go the JB Marine Weld route or ask your watchmaker to create a bush between case and tube.
Thinking back, I used JB Marine Weld and haven't had any issues.
Isn't this listed on eBay as "special quality non-original": http://m.ebay.com/itm/Insert-Rolex-Submariner-Faded-Gray-Fat-Font-with-Dot-for-Model-1665-1680-5512-/272408175381?nav=WATCHING_ACTIVE
Well, if tube is slightly too small for the case, you might need to epoxy the tube in place with Marine Weld. Here's a link to the job being done next door on a 45mm PO:
https://www.replica-watch.info/vb/showthread.php/92079-45-5mm-Planet-Ocean-Gen-Crown-amp-Tube-Installation
Go for a XVIII. A future classic, not essentially a dress watch, but it works with both suits and jeans. IWC has dropped the altimeter date and returned to a dial closer to the Mark XI: https://www.hodinkee.com/articles/the-iwc-mark-xviii-2 http://puretime02.com/mark-xviii-iw327001-v6f-best-edition-black-dial-on-black-leather-strap-a2892.html
Looks to me like the double sided sticky ring is already in place, you can just make out the 3M logo in your shot of the bezel assembly. If that's the case, just remove the backing paper and place the insert.
Not having compared them side-by-side I can't say. However, if you go for a gen Omega Seamster 300 handset you will still need to source a silver second hand, as the gen Omega is white. Personally I'd go the HR route.
You can pick up some from Helenarou, you just need to trim the tail of the second hand slightly: http://www.helenarou.com/5517-milsub-super-lume-watch-hands-correct-sec-tip-for-e551728242836.html
I've only seen one, and yes the thinking at the time was that the civilian version would be more desirable after decommissioning. And yes, there were still traces of the fixed bars visible after conversion. The only reason it was done in the first place was to enable it to be worn with a bracelet rather than a NATO strap. I'll post some shots if I can track it down again. Here's one on the Antiques Roadshow, not particularly well appraised by the expert though: http://www.bbc.co.uk/programmes/p02dl7lc