I dont think you need to be overdriven that much. what pulley dia do you have now? overheats at idle or WOT or cruising above 40 MPH or stoplight to stoplight? do you have a schroud? what # of fan blades? how far into the schroud is the fan if you have a schroud? how far is the fan from the rad if no schroud? timing/mixture in the ballpark? when did the problem start? any recent part changes/adjustments preceding the onset. what offset of pulleys do you need.