According to a friend the 742 usually needs to use small base dies to function properly and as far as he recalls his dads 742 functioned best with powders that were suitable for the M1 Garand, IMR4064,IMR4895, BL-C(2), Win748, Win760.
You could always contact Remington and see if they have a recommendation for powders or at the very least get the port pressure, then, talking to a tech at one of the various companies putting out load data may help you zero in on those powders best suited to the gas system.
Too slow burning powder can raise port pressures and this can lead to excessive wear to outright damage in a Semi auto rifle, so a little research is a good thing.