Hi Mark,
Welcome to the forum,
Ok so I will attempt some answers to your questions
If you want to fit clip ons its a fairly major job, this is mainly because the standard fork legs are not parallel between the top and bottom yoke, so it is difficult to get the bars firmly clamped, parallel stanchions are available
(hard chromed so as you dont have a rusting stanchion looking out)
You will need "gold star" type headlamp brackets, gold stars had metal fork shrouds below the bottom yoke, if you want to fit rubber gaitors you need short cup shaped pieces to fit over the fork springs and the gaitors clamp to these !!
You will need a 4:1 ratio rev counter, the road rocket rev drive is normally 2:1, driven off the mag makes it 4:1
Gold Stars use a 1:1 drive box so their rev counters are 2:1, this is not a great idea as the rev counter mechanism is spinning twice as fast and gives trouble !!!
The 54 frame is almost the same as the RGS frames dimensionally (as they all are in the major dimensions)
its similarity is why they are used for replicas,
So a Siamised exhaust for an RGS should fit
whats wrong with the headlamp in the photos??
HTH
John