I don't know what SB rates this pressure plate at but I know it held Lloyd Mills 1200hp on the dyno.I'm sure it can't take too many pulls like this but its is above 700hp for a daily driver.I don't think an NV4500 is a problem.The pressure plate has nothing to do with the input shaft size so I would think it would fit with both,1 1/4" or 1 3/8".