Wilhelm Brenneke designed the round in 1917. It is basically the .30-06 necked down to 7mm. It offers the identical performance to the .280 Remington which was developed 40 years later.
You can use .280 Remington loading data to load 7x64mm ammo. ( But take note that the two rounds are not interchangeable. The dimensions are significantly different and it would be dangerous to interchange the two. )
The 7x64mm is one of the all-time great cartridges and you can make your own cases by necking down .30-06 brass.
A good load would be a 140 grain Nosler partition bullet with 58 grains of H4831. The muzzle velocity would be about 2900 fps.