That would not be a happy place . . . on a two fronts. First the 261 is after the transition from steel to cast-iron cams - so the lifters are to soft to run on a steel cam. Second, a roller cam blank is designed with the lobes centered on the lifter bores - whereas a cam blank designed for flat-tappets has the lobes off center to the bores (so that the lifter rotates on the lobe).
