jasuz, if your bow was tuned with the 125s you may only have to some minor tweeking. Shoot a BH at 20 yds, then a field tip. Do this a couple times to see where they are hitting. Then gradually (1/32" increments) adjust your rest. If the BH is hitting left of your FT, move the rest to the right. In other words, chase your FT with the BH.
Also you are only going to gain about 5 fps. But you are going to loose a bit in the energy.
I did just the opposite this year, I went from 100 gr to 125s.