I would suggest http://opengapps.org/, but I haven't tried it yet.

You should use:

• 32bit ARM - Sailfish X only use 64bit for the kernel, AFAIK
• KitKat 4.4 version (That's the one supported by the aliendalvik on Jolla C, Tablet, and Sailfish X. Jolla 1 is still stuck with Jelly Bean 4.2, thanks to qualcomm drivers)
• either the pico (bare strict minimum for Play) or nano (pico + a few extra google services not available on the playstore).

Note that in theory, as your Xperia was licensed for Google's Android, you should in theory have the right to run google service on your Sailfish X installtion.

(But your local jurisdiction's software copyright laws might be nitpicking because you don't use the exact verison that came with your phone - by extracting it - but download a different but more or less functionnally equivalent from the web).