Definitely hope you find a good medium and comeback and show it..lol. I am horrible for finishing stuff and forgetting to comeback and share. I bet most them was custom made. Due to the nature of dirt oval.
Rc12 would work. It has the tbar out back..but you could fab up an irs if you re all want one. Use the same king pin set up as the fronts and lock the knuckles so they dont turn. Put some washers between upper and lower and you can use longer springs to have better travel? Its an idea. Lol if...