Salivanto's suggestions are good. If you wanted to use the related Esperanto name, you could also go for:
- Anastazio (Ananjo, Anastanjo)
And if you wanted more or less fidelity to the spelling or pronunciation of your name, you could also go for:
- Stejsi, Stejsio
- Stejci, Stejcio
- Steci, Stecio
What I did first was to see the history of my name: Ray, from Raymond, from Raginmunde (Old german for wise counselor.) "Rejmondo" was phonetic, but I loved "Raginmundo". I put it into Google translate which somehow turned it into "Ragworld." After I stopped laughing, I tried some others, which got even more (embarrassingly) pretentious. Then I tried a reverse translation, ragworld from english. It did not come up as Raginmundo, so I decided that it was Google's problem. Do, mia namo esperanta estas Raginmundo.