id say if you can get the 4.5 in there,put a eagle 4340 steel 4.5 stroke crank in there.i spin my4.5 inch eagle crank into the mid to upper 7000 rpm range in my chevelle.the more cubes the more power,but then on the other end chances are this is going to be street/strip application so then why spin the thing hard when low speed torque is soooo plentiful!!!