I'd shim all the bars by 1_4". I'd use all forward bars with every other thresher bar being narrow rasp. I'd cut up three bolt seperator bars and create two bolt bars. leave a gap from the missing rasp threwout the seperator side. As rotor turns a rasp will cover an area and next one in line will be blank and so on. If you have edible beans and or sunflowers you may consider running rotor sweeps. Make sure you have some degree of steep thresher helicals to prevent a second thresh on allready threshed crop. This should shed some brand new light on liking of the machine. Go for it.