69 valiant / to 340 shift linkage

The linkage from the Column to the bell crank, and the bell crank are the same. I believe the rod from the bell crank to the tranny is also the same So yes you should be in good shape.

I have heard good things about the kick down cable but havent used one yet.

The inspection cover of the trans will be different then your 904 cover. I believe big block 727 is also different.