Sounds like you are trying to put Clark/Superman into Jimmy's body. Since I don't like Jimmy it would be a problem for me.
I have to admit that basic body changes would be more of a problem for me then personality changes. Granted these would be 'Elseworlds' stories but I see those as placing our characters into environmentally different situations which would have an effect on how their personalities would be formed and the actions they would take based on that different matrix.
Aside from easily changed aspects like hair color/length and wardrobe choices, a change in the basic physical characteristics would constitute a different person to me. Unless you change the parentage,and thus the genetics, you would have different people.
Having said that, I could except a story that uses a device, such as Asabi's 'soul transferance' jewel, to put the esssence of Superman/Clark and/or Lois into a different physical body. If fact it's been done before. I believe Pam wrote a story where Lois was trapped in a different body.
Bottom line, a good story is a good story. I might feel your premise might only have a passing resemblance to a L&C story, but I'd still give it a shot.
Also, to clear up a misconception. I most definitely prefer Lois with short, dark, hair. I've used her changing to a red color for some of her disguises in some fics for a specific reason. Teri dyed her hair and had it cut short (too short in my opinion) for that bad TV movie she did during one hiatus. So I have used the red color in some instances because we already had a mental image that we could access while reading the story.
Tank (who much prefers dark brunette hair color over all other options)
