mate when I bought my vn I had to change the harmonic balancer. What I noticed was the CAS is only held in buy two bolts. Now when I bought the harmonic balancer, The spare parts place wanted to see the old one because there are 2 different parts one pre 1990 and one post 1990. the difference is the length of the blades on the back of the balancer. As far as I'm concerned the only trouble that can happen is if you butcher the harmonic balancer.
After removing the belt and radiator . The bolt on the front of the HB can be pretty tight. What worked for me was, putting the right sized socket on thr bolt on the front of the hb then attach a breaker bar and make sure you have it touching the ground on the passenger side of the car and just for a split second turn the ignition so the startermotor turns a fraction. (If this doesn't work then you will have to try something else) now get your pullers with your 6mm bolts and screw them into the three holes . then use a shifter or spanner tighten the centre bolt on the pullers until it eventually comes off. If it is stubborn, lightly tap the hb with preferably a mallet but you can use a hammer trying not to do any damage. this should exposes the CAS and the 2 securing bolts. Take the bolts out and unclip the wire plug.
I hope that helps lol. Good luck.