If you have a complete front end with wheel, caliper and m/c it's a bolt-on.
The fork tubes, upper triple clamps and lower right legs are all identical except the late models won't have fork drain plugs.
The lower triple clamps are nearly identical but the late model triple has a tapped hole for the brake hose bracket, so it's best to use that or drill and tap your early one. The boss for the bolt hole is already there.
The late model clutch perches are different and use a larger diameter safety switch. Either use your early perch or rewire the early plug to the late switch. The brake light switch on the m/c side will need an early plug end grafted to it.
The late model start/kill switch is oriented differently on the bars due to the master cylinder. If you use the early switchgear the "start" button will point at the ground.
Those are all the details I can think of. If you have all the stuff it's pretty easy.