Sorry ... Rom 10:8 is the answer to Rom 10:6. The word of faith is:
if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved.
You want to ascend into heaven? (that is, to bring Christ down from above? Exactly how are you going to do that without Him?
John 3:13 And no man hath ascended up to heaven, but he that came down from heaven, even the Son of man which is in heaven.
Vs 6 has already set the mark by saying faith is not about who ascends to heaven and who descends to the bottomless pit. So, you wrong if your interpretation of verse 8 is about those ascending and those descending.