Hi elewis,
Nice to see someone else on here that is from Illinois! First of all, you are not thinking about putting those plants in the ground right now are you? I had a similar question a month ago listed under "Grape Plant Crisis". You can see the response from grapeman, so I was thinking that a month ago was on the cut off line, but now with the cold setting in I'd wait. Second, I have found on this forum that grapeman equals grape growing expert, so you can be sure that if he responds to a question, his answer will be close to, if not right on. The guy knows about growing grapes! I only wish I had half that knowledge. I mainly mess with Concord grapes, so I don't know about Muscat, but usually you would be safe in planting them 6 to 8 feet apart. A local enologist and viticulturist told me to use two wires on my Concord trellis; one wire at 3 feet and one at 6 feet, but here again, your variety might be different. For two plants, your row should be around 18 to 20 feet long. You would put in and end post, then 6-8 feet from that post, you would put a plant. From that plant, you would go another 6-8 feet for your second plant. Then you would go another 6-8 feet and put in another end post. Check this grape growing forum and you will find an excellent posting from the grapeman, where he walks you through planting a vienyard...photos included. I'm in the Springfield area of the state, where are you located?