I need some help from one of you engineers out there.

I am changing engines on a big Stick. The new engine will be heavier than the old one. I already had to put the battery and a little lead in the tail to balance the old engine. Is there any kind of formula out there to determine how much to shorten the nose to get the cg right?

I'm already planning on putting the elevator and rudder servos in the tail. I may also eliminate the Fults nose gear which is heavy.