I just converted one of my 34" J 5 string basses to E to C. I have D'Addario Prosteels 105 to 45 on it. Currently I have a 28 on it. It works fine on my 6 string and my 35" scale E to C bass. But on the 34" J it might be a bit too twangy compared to the other strings. I can get the prosteel singles in 30 or 32. What would be the correct gauge tension wise?