Hi....I had one of those rather expensive conical jobs with a smooth profile allowing it to go nicely over a bow roller. Italian-made. Swivel part seized after one season, bolts holding it together seized too so I had to cut it off. Now have straight shackle...just goes through roller.
If the swivelling function is that important, and the bow roller no problem, why not try one of the mooring swivel jobbies, two loops with a swivel between them? Much less expensive than the Italian job I had and ditched.
Be carefull... Most chain to anchor junctions sold by schipchandler shops have a resistance MUCH LOWER than the chain they should connect::
Check this resistance not only with a straight pull but ALSO with a side way pull..
On my own boat, I'm using a very simple toggle, the same type you are using for your rigging.. but ALWAYS one size bigger than the chain (ie: 12 mm for a 10 mm chain) Look in the next PBO (reader forum) for the photo..