Short version of question: Is it appropriate to ask a higher-ranking coworker, who is in the company's management, his/her opinion or to get advice on potential decisions that the company's owner (aka the Big Boss) has sought my feedback on?
Long Version: The Big Boss has sent me, and me alone, an email regarding some potential business decisions that I have mixed opinions about. I am not part of company management and have no decision-making power. I am in charge of a project that is directly involved in this decision-making process. Whatever decisions get made as a result of my project will affect several other people, as well.
I'd like to share this email with one of my coworkers who would be affected by these decisions for the sake of getting his advice on how to respond. This coworker is higher-ranking than me and is in a management position within the company. He would ultimately have a say in the final decisions, so it's not like the email has any information that would be withheld from him.
Essentially, I'm concerned about these decisions being made to support me and my project without reasonable input from other parties. I have explicitly voiced this worry, but I feel like it's fell on deaf ears. I also get the sense that I'm repeating the same concerns over and over and that they're going ignored, so getting a read on whether my opinions are on-target or not would be nice. But I'm not sure if contacting someone in company management is appropriate. What is the best way to go about soliciting my coworkers opinion on this matter?