I suggest you forget about what powder they used, and load the rifle normally with normal powders available in your area, with data prepared by the powder maker.

: I had a 6mm Rem Parker Hale Varmint rifle back in the 70's. This Mauser actioned rifle, with IMR3031 powder and 70 gr. McCracken bullets agg'd in the 2's. It was barely accuracy enough for shooting deer to 200 yards with normal bullets, as in 1.5MOA, but with those light varmint-type bullets it thought it was a bench rest rifle.

My cousin still has the Parker Hale .243 I insisted he buy back in 1968. He will not part with it.