Our buddy kei17 has reached out to a friend who lives in Akita Prefecture, Japan, to find out exactly what measures Toei Animation has taken with the musical score. It should be noted that in Akita Prefecture the broadcast of Dragon Ball Kai is 17 days behind that of the most recent episode and airs on a Wednesday at 4:30PM. Here is the reply he received from @syoujikimura:
Yesterday, in Akita the episodes up to Gohan’s awakening have been broadcast, but the opening title display, the sub-title BGM, and then all the BGM throughout the show has been changed to the Z stuff. The OP, ED, CM opening and closing, and the seiyuu’s voices have been left the same as in Kai.
So it appears that Toei Animation is not taking any risks and is entirely replacing Kenji Yamamoto’s Dragon Ball Kai score with Shunsuke Kikuchi’s original Dragon Ball Z score. The only pieces left intact are the opening theme (“Dragon Soul”), the ending theme (“Kokoro no Hane”), and the eyecatch music, which are based on “Dragon Soul”. Note that none of these remaining themes were composed or arranged by Yamamoto, which is most likely why they were retained.