I would not speak or write the phrase the way you have listed unless I was quoting someone or in an environment where slang is perfectly acceptable.
I would probably say something along the line of, "..if they were" as you have mentioned or just restructure the phrase altogether.
Please don't interpret this as being a snob. I am assuming this is in a written format.
As far as I'm concerned, slang is perfectly acceptable as long as the thought is clearly conveyed and no one has been intentionally offended.