This will display the display name of the sign in text above it... if this is what you're looking for? I'd probably make a new template from the existing one and use that for your sign.

Code
IF
CharacterUsedItemTemplate(_Player,"BAN_Banners_Citz_SidewalkSign_Chalk_B_8f088290-03ef-43b9-84cd-ed90df213f22",_)
AND
ItemTemplateGetDisplayString(ITEMGUID_BAN_Banners_Citz_SidewalkSign_Chalk_B_000_f761fa06-55fe-4941-aabf-7f3190705c2c, _signHandle, _signDisplayText)
THEN
DisplayText(ITEMGUID_BAN_Banners_Citz_SidewalkSign_Chalk_B_000_f761fa06-55fe-4941-aabf-7f3190705c2c,_signDisplayText);