no spark on 1983 honda cb250rs dc deluxe?

no spark on honda cb250rs dc deluxe, electric start tried new cdi unit, mechanic tried another altenator assembly. my local mechanic currently has the bike i do not work on it myself. he suggested a new wiring loom

was running well then started to cut out then eventually wudnt start

will an xl engine fit directly into frame?

Any suggestions welcome