I'm wondering; assuming you have a 39 jet in there now, and you put in the 56, that's a 106 % increase in area, but why wouldn't you want to change the low-speed? If you have a 19 jet in the low-speed now, and you want to increase it by about the same percentage, it would take a 27 jet.
A change from 26 to 27 on the low-end is about 8% change in area. A change from a 55 to 56 is a change of, about, 3.6%.
For sure I don't know which way to go, but information is information. More information can't hurt.