Here, I did some work for you. http://www.clarkracingchassis.com/new.htm

Keep in mind that the tire/wheel combo also covers all of those axle tubes right up to the beginning of the pumpkin. Where in god's everliving green earth are you going to put IRS? If you and your advanced knowledge of chassis engineering can figure out how to change physics and somehow make it work, you've earned my respect. Again, the tire contact patch is what is important here and as such, you're just not going to fit an IRS design in there. Period. I HOPE that is clear enough for you.