A caution: whatever method you use to jig the tail surfaces, don't force any parts into position. If you do, they will move after being taken out of the jig, and be crooked anyway. Better to block the stab in position, tack glue, and then fill any gaps with shims carefully sanded to fit.

Also, be sure the fuselage is stiff before you glue the tail on. Not a problem with ARFs. But when scratch- or kit-building, if the fuse hasn't been fulled planked, it can still twist.