This weekend I got my aftermarket SeaMaster bracelet, ordered from
WATCH BAND BRACELET FITS OMEGA JAMES BOND 007-20MM SEAMASTER | eBay
(hope the .de link works)
I found, that the endlinks where too short for a nice fit on the Estoril. Then I noticed, that with the original Borealis springbars the gap disappears. The delivered spring bars which came with the bracelet where too thin, only loosely filling the drilling in the endlink.
One of the Borealis spring bars did not really catch the drilling of the lug because now there was no play at all. But after 10 min easily grinding the endlink, the spring bar finally snaps in.
The number 825 of the end link should be a hint for Seamaster compatibility I guess.