By no means was the ß abolished. The spelling reform set different rules for the use of ß and SS, depending on the preceding vowel. If the vowel is long, then one is the correct letter; if it is short, then the other. Far from abolishment, it actually made SS incorrect in certain uses.
Unfortunately I don’t know enough about the spelling reform to be absolutely confident about its implications; but if memory serves, then ß is appropriate before long vowels and SS is appropriate before short vowels. Therefore, I think the correct spelling for the word given above would be Schlossstraße.