The KO threezero Optimus (MC-003) CAN do the combination with jetfire! Some parts are ever so slightly wrong or need to be fixed in some way but it is very possible :
Takara Transformers Micron Legend Hot Rod S (Super Mode) MC 13 | Mandarake Online Shop
Moving Coil Transformers for DIY [English]
intact audio
Metal Club MC Die-Cast Robot Mecha Action Figure MC003 (Transformers Optimus Prime) Action Figure - Sugo Toys | Australian Premium Collectable Store
mc step-up transformers explained
Lundahl MC Phono Step-Up Transformer Kit - DIY Tips & First Impressions - YouTube
Amazon.co.jp: Transformers Legend of Micron MC-09 Vice-Commander Jet Fire Takara : Toys & Games