The 79-80's (commonly called the "twin-shock") have a lumpier cam. This makes them a little more aggressive than the pro-link. It was the 1st bike that had to be detuned for Germany's "new" 100BHP rule (it puts out 105BHP).
The instruments are bigger than the 900F/1100F - apparently this is to create the illusion that the bike is not so big.
The twin-piston brake calipers from a 900F will bolt straight onto the CBX fork legs (and are MUCH better).
The front brake master cylinder from a VF1000F will bolt straight on, looks standard, and DOES NOT LEAK like the original does.
Check the thin main fuse. If it hasn't already been changed it will disintegrate in your fingers.
ALWAYS turn the fuel off when parked! If a bit of grit gets into the left carbie it can hold the float valve open. Due to the angle of the carbies the fuel may get into the left cylinder. When you fire the bike up the resulting hydraulic lock will bend the conrod. The pro-link's went to a vacuum fuel tap, but the manual one is much better.
If it won't start up after a long layup, drain the carbies, refill, and it will fire right up (I don't know why, but the float bowls seems to make the fuel go stale very quickly).
The twin-shock airbox may fade & make the bike look terrible. The pro-link airbox fits straight on and has replaceable plastic inserts on the side (it looks much better).
If you win the lottery, buy a set of these. I've heard them, and they are AWESOME!
http://www.pipemasters.net/cbx6.html