Which of the lams is going over the back, the 90 or the 120? I’ll presume its a taper? If so, prior to making the splice you might try running the butt of each lam through the drum sander on your parallel sled, just enough that you’re taking the butt down a bit , but stop before you get down onto the fade. If its an .002 taper, then even 5” will get the butt slimmer by .010, maybe enough ? What glue are you using? CA? Remember that any glue requires a full cure, and even CA benefits from curing overnight.