Hi-
The back brake drum can go oval- just ride and touch on the back brake to check for roundness. Also the tappets/ cam tensioner can cause top end rattling. the electric starters can cause problems. The petrol tanks can leak on the front bottom seam- check for filler. The rear seat covers are getting like rocking horse *******e. Original twin exhausts again difficult to come across. The bike may have an aftermarket single motad or micron now. You can get stainless single side for about £325 Just check over the bike for usual stuff- easy starting from cold, suspension, electrics, frame condition etc
The f is an earlier model and the h a later model. The h will have the front indicators drilled through the headlight mount and a lump in the starter cover as opposed to flat on the earlier models. The h may be in silver as that was a later colour
If you get one and need any spares give us a shout
Cheers- John 07990 810934