hey glad you are making some head way and got it started.
the drain plug and feeler plug for the trans should be behind the cvt cover back at clutch bell at back of engine.

i don't know what to tell you on the other parts unless you go new,which there is going to be a several bucks involved.
don't hardly here of some one bringing one back from the dead. most usually some one goes with different engine set up.
i don't know of any one parting out a gk-13 titan style buggy
maybe some others can get you lead on some stuff.

pud

i am confused too. i have two of these go-karts and the engine is stamped with cf-moto and cn250. drive parts have the same stamping on them too.