Unfortunately I don’t think there has been a fan edit for the 1980 version of Flash Gordon (here or elsewhere) - though I hope to be wrong on that.
I’ll have to check the fanedit forum some time, maybe there will be something there.
I used to admire the costume design of the 1980 film a great deal, until I watched the documentary about Jodorowksy’s Dune (brilliant documentary by the way). Towards the end of the documentary there is a series of comparisons of original designs for the unrealised Dune project and the films that followed in its wake. It makes for rather depressing viewing.
That said, Ming’s palace guards (the ‘pig guards’ and ‘football players’) and the secret police costumes in particular are fantastic.
George Lucas developed Star Wars because he could not obtain the Flash Gordon rights. I wonder if his version would have been anything like as colourful, had he made it.