Sorry for the delay, been DH diving on Bonaire with Luis, Simonbeans and ScotttyD.
To clean the hoses and mouthpiece toss them in the washing machine with some towels and a little bleach, although if you intend to dive the reg much, new hoses and mouthpiece are a good idea, even the best old ones are a lot stiffer than the new silocone ones. Reguardless of how the main diaphragm looks, replace it. Like the hoses, even the best OEM one is no where near as good as a new silicone one, the performance gain with a new diaphragm is considerable. The original style (has tabs) diaphragm can be reused with an HPR so it's not a wasted part, the newer one intended for the HPR is slightly better but it will not work with the standard second stage. In addition to the other parts, you will need to replace the duckbill or install a duckbill eliminator. The DBE is $10 more than a duckbill, it is easier to install correctly (db can be a pain to get right) and it works better to boot. Here would be my suggestion for your parts list with comments.
Main diaphragm- reguardless of original ones condition, performance gain is well worth the money
Duckbill or Duckbill Eliminator- you must do one or the other, I have yet to see an original DB in usable condition
Service kit - the kit does not include a HP seat, you may can resurface yours but replacements are $15, not a bad idea to at least have one on hand
Hose valves - another must replace, again none from the day are good enough to reuse
Hose clamps- Can't tell about the mouthpiece ones but the can end ones are the very old model. Odds are they are brittle,you need to replace them.
Nice to have parts
Band clamp- those C clips are a PITA to remove and replace, it best done with special tools. For any reg you intend to dive it is a must have IMO
Hoses and mouthpiece- while those may apprear good, no OEM ones are as soft as the repro silicone ones
Tools for the job - most you can work around but it does make the job more difficult, esp the first time it's appart after 40-50 years
nozzle assembly tool- HP nozzle assembly is not too bad on the DAs but RAMs, Phoenixes and Cyclones are a huge PITA to do without one
body ring tool- removes the main body ring
body wrench - holds the main body during disassembly/ assembly
hookah port adapter- not actually a tool but you must have some way of checking and setting IP. This adapter converts the hookah port to a standard 3/8 LP port to which you can connect an IP guage, this part is a must have.