I have 120g 4ft at first i would like to introduce A atlantic blue,clown tang,powder brown.
I have 2 tang in there now but the will be rehomed yellow and salfin.I have 4 wrasse and a file fish. Next i was thinking. Scopas and and last to introduce a orange shoulder or Achilles
All three of those are acanthurus tangs and without proper treatment and quarantine the odds of success are low that they won't die of ich or other parasites.
Add to the fact that the clown will definitely outgrow that tank and I might advise a different genus of tang altogether for a 4' tank.