by dtc » Wed Jun 21, 2017 7:51 am
As jaffa indicated, what do you mean by 'short board' - do you mean a point nose rockered 'high performance short board' (HPSB)?
At your size, most HPSB will be fine - if you are skilled enough. If you can surf your 5'8 fish well and properly, then probably something around 6ft or slightly shorter, 19-20 inches wide. there are 100s of varieties, what the actual difference is between them all who knows!
If you are still a bit on the beginner end of the spectrum, then maybe something more egg shaped and a bit wider and thicker and probably longer. So something in a 'hybrid' style like a hypto krypto or average joe around 5'10 - 6ft (will be 21 inches wide and 2 3/4 thick), or something like an HPSB (narrower and thinner than the hybrid) but just longer (say up to 6'6).
that said, if you are closer to beginner and really have only surfed your longer boards, then completely different story. try a 6'8 or 7' funboard
Having blathered on - as Jaffa said, go to your local store and have a look and ask. Ask others who surf in your area or just check out their boards. Just keep your ego 'in check' in terms of your actual skill level