they are both available (drum/disc). The engine covers itself are the same as the 180cc series.
But !!
Watch out.. some types have problems with structure and they can break !!! (mostly the types with the drum brakes)
Probably you've allready read that @ T&G more then once
If you want to start with empy engine covers: try the SIP Performance special covers
Runner 125 was available with drum and disc brakes, but i don't know exactly which engines were used during which year...
Cheers bud i may attempt an idea going around thats probably already been done, well done by one guy i know already.
125 runner engine 172d then slapped into a zip!!