Dinner and a Murder Mystery Games

I am new to murder mystery parties and am hosting the Four Deuces (tame) in two weeks. I'm very excited, but I have a little problem...
I invited 40 people and so far no one has declined the invitation. I have purchased both extra character packets, but I have 27 girls and 13 guys, so the ratio is very off!
I have been reading the posts on this site and realize that you cannot change the main character's genders because they have relationships and things would get tricky. I was wondering if possibly I could have some girls play male extra characters? I thought that since the other characters don't have information about these characters, no one would no the difference.
I'm open to any suggestions you have, and thanks in advance!

You can always have girls play guy characters. It would be best to do this in the extra characters, than in the main characters, since you have enough people to fill the main ones.

OK, I'll try that then.
I have another question :] Would you suggest giving each person their character information (not confidential) ahead of time or at the party? I want people to know their characters but I'm afraid that the murderer will tell everyone!
Also, I will tell Big Jim he is the victim, but is it OK if some others know he will be murdered?
Thanks so much for your quick response!

Would you suggest giving each person their character information (not confidential) ahead of time or at the party?

ABSOLUTELY

I want people to know their characters but I'm afraid that the murderer will tell everyone!

Every background states the following:

Other than informing people who your character is, it is important that you DO NOT discuss your character’s information with anyone else before the game starts. If you do so, you are likely to give away secrets and spoil the game - mainly for yourself & the person you told! This is especially true if you are the killer!

Now that being said, I would still recommend repeating it to everyone if you speak to them. I have heard of some really rude spoilers from the person playing the killer. Only twice, but in my book that is twice too many!

Also, I will tell Big Jim he is the victim, but is it OK if some others know he will be murdered?

It really is best if they are surprised that a murder takes place at the party. While this is a murder mystery party, a lot of games have the murder before the party or they use a dummy. Our games stand out because we don't usually do this and it gives a dramatic and fun event to your party.