Can I fit a 91 primary to a 99 motor

I have a 91 Softail that was flooded. I am rebuilding it for my wife. My current plan is to tear down my chopper and take the 99 Evo (built in 2005, but a 99 model) and place it into the Softail. Later, I'll take the 91 motor and rebuild it and use it in the chop. Anyway, I want to use the 91 primary drive (inner, outer, etc) with the 99 motor. I assume it will bolt up, but I also figure there is some part changes I need to make (internals)....can anyone help me with this. I'm using the 91 frame, a Ultima 5-speed transmission (basically a harley knock-off), and the 99 evo.