Well... Male Justice League performer... Be able to play the part of a Male in their early to mid 20's ... American accent ... strong physical likeness to a superhero ... 187cm and maximum height of 193cm...
So what male superheroes have been in the JL that are younger, american and built "like a superhero" and are relevant enough that they would have a new character in park...
Male:
Superman, Aquaman, Green Arrow, Atom, Cyborg, Shazam, Nightwing...
Now they say new so if you go completely literally (which I usually do)... Superman and Nightwing have been characters in the park before so they would be returning not new... (Then again "new and improved"... Well which one is it?)
Height (approx): Superman is 6'2" (187cm), Aquaman is 6'1"(185cm), Green Arrow is 6'2"(187cm), Atom is sort of not entirely known but about the same as Superman, Cyborg is 6'8" (203cm), Shazam is 6'2"(187cm) and Nightwing is 5'10"(178cm)
From personal experience they do not specify certain things in their employment notices which are a deal breaker straight away (call for character performers, I was only male, they pull me aside and tell me it is for the Lola Bunny, Tweety and Daffy characters which at the time were all female only performers so told not to bother hanging around)... They do not specify race... Given superheroes are portrayed as a particular race this is an important hiring factor and is necessary for the role so it is something they can specify in the notice... Being male is and they have... Short of that paragraph is we cannot count out a particular character based on race...
Take from all this what you will but my money is on the Man of Steel especially given the Doomsday Destroyer currently being placed and other than Cyborg he is the only character in the JL3D ride that does not currently appear in park.