I am in the middle of swaping my 258 for a 1992 4.0. I have a Holley Sniper BBD and a HEI distributor that I will install on the 258 intake manifold as soon as I finish port matching the intake. I have the block in the jeep and have the oil pan and valve cover and timing cover in place and am trying to find a water pump that I can use to maintain the V belt set up. Eventually I want to add a York air compressor. The engine that I swapped in has a crank that is setup to use a V belt pulley from my original 258. I would like to use a Flowkooler pump because they are supposed to move significantly coolant under 3000 rpm. I have not been able to locate any information regarding putting a water pump for a 258 onto the 4.0 or finding a 4.0 water pump that will accommodate a V belt. Any thoughts or help would be much appreciated.