Here some of the parts that would be required:
1. .223 barrel, Bulgarian,
2. .223 bolt, Bulgarian,
3. .223 magazine that would fit, possibly a Galil magazine,
4. may have to lengthen the ejector to work with .223 cartridge.
Would be easier to look for a used Romanian SAR3 in .223.
AK Romanian SAR3 SAR-3 .223 $750 NR 223 : Semi Auto Rifles at GunBroker.com